The number one thing is look at several examples of their work and make sure you'd be happy if it was hanging on your wall. Forget about the price difference, you won't even think about the extra $100 after you walk out of the shop. Higher price doesn't mean better quality, the $200 guy could be better than the $300 guy. The best taxidermist I know of gets $250 and he does amazing work, guys come from all over the state to get him to mount their bucks. He mounted the state record non-typical and every year you see several of his mounts in North American Whitetail magazine. A couple of other taxidermists I know of get $350 and their work isn't nearly as good. Often times the younger taxidermists do better work than the old timers. Taxidermy techniques have improved dramatically over the last decade, the old timers often don't keep up with the times and their quality suffers from it. Stay away from the guys that do it as a part-time job, they could be good but usually they don't do work as good as the professionals. Last thing, don't be afraid to ask around amongst the local gun and sporting goods shops, if you're in an area where deer hunting is big then you'll probably see a consensus of who's the best taxidermist in the area.