Facebook users could face higher prices

Paul Sakuma/AP/Press Association Images

You may think your use of Facebook and Twitter is fairly savvy. You may regularly 'like' or 'retweet' information about companies or products in order to win something or qualify for a special discount. However, one expert is warning that in the long run these things could end up costing you more.

The phenomenon we should be wary of is 'behavioural pricing'.