Well, I don't know if you have access to such a facility, but at Penn State, there is a place called Salvage, where old (and sometimes non-functional) equipment goes. People may then buy this old equipment. I purchased three scanners from them and the last one worked ($15 each). It is an HP ScanJet 4c and works quite well with Debian. I had it installed when I ran RedHat and switching to Debian didn't affect a thing. Also, SANE and Gimp work just fine with it. The only little catch was getting the permissions right, so non-root accounts could scan. Good luck.
Brian