The Goodwill Computer stores are a mixed bag. Sometimes you can pick up a good item or two, but a lot of the stuff tends to be overpriced (namely the older stuff). I did find a bunch of NOS DS/DD 3.5" floppies there once though. (They were from approximately 1988 and all but one of them worked).

I'll be going to mine again sometime in December. Does anyone want me to look out for any particular items? (Most of the store is Wintel parts, but there are occasionally some good Mac items too).