I have no problem at all “making an offer” on a revolver that interests me. Just like a price from a seller that can always go down, if he chooses, my offer can always be adjusted up, if I choose. I don’t make crazy, low-ball offers, and if the seller is offended by my suggestion, I guess that’s too bad. I probably don’t want to do business with that type of seller anyway.
Do a little homework and see what the asking prices appears to be for similar revolvers on some gun websites, maybe excluding the ridiculous one(s), and make your offer based on the value the gun would be to YOU. ($1000, for example, is “worth” different things to different people.)
It is hard to make a guess on a gun without good pictures.