There are all sorts of simple ways to boost your bank balance, from taking part in a boot sale to taking up direct selling in your spare time.
But what about a more unusual way to make money? Flu Camp is paying volunteers thousands of pounds for taking part in medical trials. Let's take a closer look at how it works.
What is Flu Camp?
Flu Camp is a medical trial facility in Whitechapel in London.
As the name suggests, volunteers are given the flu. Some will just be infected, some may be given an external vaccine before the test begins, while others will be given anti-viral drugs after infection.
The trials involve staying at the facility for between eight and 14 days, where you can be monitored. You get your own room, with an en-suite bathroom, and there's plenty of entertainment on hand in the form of games consoles, TV, computers and the like.
You'll then need to visit the camp daily for a little while after the trial so that the staff can monitor how you are recovering.
Is it safe?
Safety is an important question. After all, back in 2006 a trial testing a drug which tackled leukaemia, arthritis and multiple sclerosis hit the headlines, after a number of volunteers suffered significant side effects including vomiting, organ failure and head swelling.
I spoke with Dr Rob Lambkin-Williams, who was keen to point out that with Flu Camp the infections and drugs given to the volunteers have all been tested before. As a result it's highly unlikely that you'll experience such extreme side effects.
The staff at Flu Camp will also monitor you for a while after the trial to make sure you are recovering appropriately. If you take longer than expected to get over the infection, you may be asked to come in a little more frequently.
Who can take part?
Volunteers need to be aged between 18-45 and in good physical health. You won't be able to take part if you have any underlying condition which may be negatively affected by the trial, such as asthma.
To be accepted onto a trial you first need to complete the online form. You'll then take part in a telephone screening, which will go over your basic medical history.
After that, there's a panel screening appointment and a full medical to get through.
Once you've cleared that, it's on with the trial! According to Dr Lambkin-Williams, around 20% of people who initially express interest make it through to the trial itself.
Exactly how much you get paid for taking part depends on the trial involved and how long you need to stay at the camp. However, you can earn between £2,500 and £3,750. For a couple of weeks feeling a bit rough, in a pleasant facility with your own room and en-suite bathroom, that doesn't sound the worst deal in the world!
The money comes from whoever is behind the test. So it may be the developers of the drug, it may be a university, or it may be the people behind Flu Camp itself who run their own experiments.
Can you do more than one trial?
You can take part in more than one trial too. Of course, having taken part in a previous trial limits your options a little as you may now have antibodies that would rule you out of certain tests.
And the staff at Flu Camp monitor volunteer databases to check you haven't been doing too many clinical trials as this may interfere with the results.
The view of a volunteer
A friend of mine, Alan Hunter, took part in a Flu Camp trial a couple of years ago, so I picked his brains on his experiences.
He noted that he had been a little daunted by the prospect of the panel tests as he'd never had to do anything like that before, but was immediately put at ease by how chatty and friendly the doctors and nurses were. The physical tests were fairly mundane; the sort of things most people have throughout their lives (things like blood tests, measuring height and weight, questions about smoking and drinking habits).
When the trial itself began, everyone was extremely professional and far less chatty. In his words: "I preferred that, as I didn't want to feel like I was being treated by Dr Nick from the Simpsons."
Further tests took place prior to the injections and then the vaccinations began with each volunteer injected at 45 minute intervals. Alan's fellow volunteers were all young (plenty of Australians and students apparently) so it was a fun stay.
After the trial had finished he had 20-30 further appointments, ranging from popping in early in the morning to have more blood taken, to having further vaccinations under supervision. He said that if circumstances allowed, he'd be more than happy to take part in future trials.
Would you do it?
With a wife and young child, I'm not sure I'm an ideal candidate for Flu Camp, much as I'd like a fortnight away from changing nappies.
But I can see the attraction. You are testing drugs that have already been studied at length, in a welcoming environment and you get paid incredibly well to do it. But there is also that nagging doubt in the back of my mind. By the very nature of medical trials, there is always some risk involved.
What do you think? Would you give Flu Camp a go? Or is it not worth the money? Let me know your thoughts in the comment box below.
10 of the biggest consumer rip-offs
Flu Camp: make £3,750 by getting the flu
Using a mobile phone to make and receive calls, send texts and browse the web while abroad can be extremely costly – especially if you are travelling outside the European Union (EU), where calls can cost up to 10 times as much as at home.
To avoid high charges, Carphone Warehouse suggests tourists ensure a data cap is in place, use applications to check data usage, turn off 'data roaming', avoid data-intensive applications such as Google Maps and YouTube and use wi-fi spots to update social networking sites.
Payment Protection Insurance (PPI) is supposed to help people to continue meeting their loan, mortgage or credit card repayments if they fall ill or lose their jobs. However, policies are often over-priced, riddled with exclusions and sold to people who could not make a claim if they needed to.
At one point, sale of this cover - which was often included automatically in loan repayments - was estimated to boost the banks' profits by up to £5 billion a year.
Now, though, consumers who were mis-sold PPI can fight back by complaining to the bank or lender concerned and taking their case to the Financial Ombudsman Service (08000 234567) should the response prove unsatisfactory.
It could be you, but let's face it, it probably won't be. In fact, buying a ticket for the Lotto only gives you a 1 in 13.9 million chance of winning the jackpot.
With odds like that, you would almost certainly be better off hanging on to your cash and saving it in a high-interest account.
No-frills airlines such as EasyJet may promote rock-bottom prices on their websites. But the overall fare you pay can be surprisingly high once extras such as luggage and credit card payment fees have been added - a process known as drip pricing.
Taking one piece of hold baggage on a return EasyJet flight, for example, adds close to £20 to the cost of your flight, while paying by credit card increases the price by a further £10.
It may therefore be worth comparing the total cost with that of a flight with a standard airline such as British Airways.
Cash advances, which include cash withdrawals, are generally charged at a much higher rate of interest than standard purchases.
While the average credit card interest rate is around 17%, a typical cash withdrawal of £500, for example, is charged at more than 26%.
What's more, as the interest accrues from the date of the transaction, rather than the next payment date, costs will mount up even if you clear your balance in full with your next payment.
Supermarkets such as Tesco and Asda often run promotions under which you can, for example, get three products for the price of two.
However, it is only worth taking advantage of these deals if you will actually use the products. Otherwise, you are simply buying for the sake of it, which is a waste of your hard-earned cash.
Buy a train ticket at the station on the day of travel and the price is likely to give you a shock - especially if you are travelling a long distance at a busy time of day.
However, you can cut the cost of train travel by 50% or more by going online and making the purchase beforehand - especially if you book 12 weeks in advance, which is when the cheapest tickets are on sale.
Other ways to reduce the price you pay include avoiding peak times and taking advantage of so-called carnet tickets, which allow you to buy, for example, 12 journeys for the price of 10.
Most High Street banks offer packaged accounts that come with monthly fees ranging from £6.50 up to as much as £40, with a typical account charging about £15 per month.
Various benefits, such as travel insurance and mobile phone insurance, are offered in return for this fee. But whether or not it is worth paying for them depends on your individual circumstances.