There are too many variables to be able to give you a really meaningful answer. Quality of gun, rarity, condition, name recognition of maker, style or type of gun, collector interest, etc. all contribute to price. One gun could be overpriced at $200 and another underpriced at $20,000. You need to study the guns and the market for some time to begin to get a feel for values. As a starting point, you could check items offered by Flayderman, Flannigan, Gunbroker and other sellers. Flayderman has also published a guide to antique arms & prices - which is a good guideline but not a bible. Visit gunshows (those few that cater to antique arms) but realize that show prices are asking prices & not values - but those prices will set a ceiling of sorts. Enjoy the journey - it can last a lifetime.