There are people who appraise wildlife mounts, of course you have to pay them. The value of taxidermy specimens will depend on the age of the specimen, the skill of the taxidermist and where the animal stood in the record books if at all. You may want to think about donating it to a natural history museum or a wildlife conservation organization to be auctioned off at one of their fund raiser functions, either one could give you a tax deduction if they are a 501 3C organization. Most of the time, the value of a mount lies with the person who took the animal and the memories that come back when they look at it.