Define "cheap". I can find them for $40 and up, but to me that's too much for a ~750 MHz box, especially a no-name off-brand one. I think $25 is plenty, and that's about the max I figure I can spend. A freebie PIII would be wonderful, but I sure can't find them.
I never thought I'd care to have a vanilla PC either, but my G3/300 is starting to feel slow for the server duties it handles now. I figure since it's just Linux and nothing special that requires a Mac, why not get a x86 box since Linux is better supported there?