Mark brings up a good point. Looking at the sale price of completed listings of handsaws, for example, I think, will exemplify this quite well - good photos and a good reputation go a long way with saw prices. (Of course, a lot of the price differential there is someone skilled tuning and sharpening the saw in question as well)
When doing this research, make sure you look at completed*listings, and of those listings that have sold, look at a few of them. There's a few tool sellers out there that list things at incredibly high buy it now prices, and leave it up to see what sticks. Sometimes they're lucky, sometimes something stays there for years getting lowered every month or so. You can see how some sellers who don't know what to charge for something often get caught up and and also price their things rather high, seemingly based on the high prices someone else is asking. (And probably not actually getting.)
If you're looking for maximum return on a tool sale, it seems like the best thing you can do is wait until just after Chris Schwarz or Popular Woodworking mentions the tool somewhere.
" Be willing to make mistakes in your basements, garages, apartments and palaces. I have made many. Your first attempts may be poor. They will not be futile. " - M.S. Bickford, Mouldings In Practice