Older Macs weren't really cheap until 1998-1999. The best deal I saw pre-1998 was a stripped LC at a secondhand computer store for $25 without a monitor (I don't recall there being a keyboard or mouse either). I'm not sure if it even worked. In the mid-1990s, a compact could still fetch a few hundred (keep in mind a Classic II could have been only two years old in 1995).
Pre-eBay, the best way to get them was through the classifieds in your paper. Remember those? They didn't start turning up in school surplus or yard sales until around the time eBay came along. You could also check a computer shop to see if they had one sitting around. I got a Plus at a store specializing in upgrades in 1999 (this was the first Mac I bought to go alongside my LC and essentially the one that started my collection). It cost $50 and came with 4MB RAM, MS Works 2.0 (including every manual), a dust cover, and an external hard drive (a 20SC case with an 80MB drive inside). Original boxes for both the Plus and hard drive were included. (The only missing items were the little yellow disk protector and the Mac Plus manual). The man who ran the shop tossed a pair of LocalTalk boxes in for free so I could connect it to my LC. He also had a IIx and some sort of LC/Performa 500 series for sale. (I still have that Plus--it's one I'll never part with).
School surplus was huge from 2000-2005. Many of my Macs were acquired that way, including an iMac G3 (in 2005!) and a Color Classic. (Schools usually had tons of IIes, IIGSes, Classics, LCs (all models), occasional SEs or Pluses, a ton of ImageWriters, and later on the 5xx/5xxx computers in these sales).
