To be honest mate, i have no idea. pretty sure most vets differ in price. i believe there is a list on this site somewhere of reccomended reptile vets.
shouldnt be too pricey for them to just look at him and put a turd under the microscope and have a look. unless there is something wrong, then it might get pricey, but hey ho, all part of the upkeep lol.
might be an idea to just phone up for a quote when you find one.
its defo a good idea to get it done though, just to check there are no underlying issues before you start, its easier to keep a reptile healthy than it is to nurse it back to health from a bad knock!