But there will also be personal costs to many people. For those obsessed with the Saxe-Coburg-Gotha family (yes, that's William's real family name, sounds English, doesn't it?) there will be endless commemorative mugs and tea towels with Kate Middleton's face on them.
Say the average royal-obsessive wants to remember the day for the rest of his life. He could buy a set of six mugs for £12, six more teacups and saucers for another £12.
Then there will be bedspreads, and other household goods, perhaps another £50. Another £30 could go on flags to wave and Union Flag hats to sport at a jaunty angle.
The day itself will mean a night in a London hotel the night before and after, not to mention rail travel and meals – say £400. If he wants to take the whole family, that could easily hit £1,200.
All told, that is £1,544. Quite a tidy sum.
However, for those who couldn't care less about the marriage of two people they don't know, the costs are even higher.
First a subscription to a DVD rental firm so he has something to watch other than endless coverage of Kate Middleton walking shyly along the road will be about £10. A good book will be £8.99.
Then there will be the sunglasses so his neighbours can't recognise him and ask him if he is going to camp out on the streets to see Kate's car drive past – another £30 for a good pair. Shutters over the windows could cost £200.
A nice trip to somewhere they don't even know the wedding is happening – say, Namibia – will be something in the range of £2,000 for five days. Altogether, he is looking at upwards of £2,249. And that's without loss of earnings.
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