briantrumpet
Timewaster
Brian's ebay find looks pretty good, the main issue is you don't have anyway of knowing (in a lot of the listings) whether there are any significant audio issues or speaker buzz if they've been treated badly.
Ultimately you need to decide what your budget is - and as Brian said, you normally get a decent price for resale if you decide later to get rid of them.
There were lots of them at around that price, so should be possible to choose a reliable seller. FWIW, they work more than passable as keyboard amps too, and vocals reproduce decently too.