Fees are often very low, and CD sales help a lot. The Boat Band sells at £10 on a gig(thanks, Will Fly!), and honestly doing it for less would not be a good idea for a number of reasons. Obviously if people have a salary from a day job they can afford to give them away for a fiver, but I really can't. I honestly don't think that lowering the price would generate enough extra trade to make it worth while.