I've had a bunch of them over the years. I've had them set up to use in a couple of shops and had one that I would take to local history events, set up so kids could drill holes. I used mine in my garage to drill holes in heavy steel as my powered drill press was too high speed for big bits. I also have a set of auger bits with 1/2" shank to use in wood. As mentioned, make sure it is all there, and if you might use it someday, I would avoid one that had an electric motor running it, as there may be more wear to it from extreme use. I think that I'm down to just one left, and I don't have a good place to install it at the moment, but I'm working on finding a place. Around here I have seen them sell for $25 and up at local auctions, but a nice one would easily be worth more to me.
Make sure the crank arm is there, and if it has the advancing mechanism, check to see if it is complete. I see a lot of them without the table, too.