Q. Is there a site that doesn't charge a booking fee? And how much are other sites charging on average?

A. Priceline does not charge, and most airline sites do not as well, except for US Air and Allegiant as far as I know. Keep in mind though that if your travel dates are flexible, you'll
have a better chance of finding a low fare on Travelocity, Cheapair, Cheaptickets, and Orbitz, because these sites have excellent flexible date search functionality. These sites do charge between $5 and $10, but if they save you many times that, it may be worth it.