I would suggest going to kyclassifieds.com and placing a "want to buy" ad under the gun section. Creating an account is free, as is posting an ad, and you can put the specific amount you are looking to pay and what type of finish you want on the gun. This will allow you to make a private sale with another resident of Kentucky and save you from having to pay sales tax. I've sold a few guns on this site, as well as purchased a few, but most people want new price for their used firearms. You will occasionally find a good deal, and in your case you are stating the amount you're willing to pay. If you're going to go the used route on a firearm, another perk from buying directly from the private seller is often ammo, holsters, etc. will be sold with the gun, especially in the case of something like a .50 Desert Eagle that accessories won't be useful on any other platform. Good luck.
Carry Safely, Carry Proudly, Carry ALWAYS