Yeah, the cheapest for just the motor alone or one with chuck & stand included I've seen is ebay.
If you just want to replace the motor itself the turntable motor on an otherwise dead microwave oven works great and in a lot of cases it's the exact same motor as on the Pac-Bay American Tackle wrapper/dryer units.
My motors came out of an old copy machine. Of course that was twenty years ago so I don't know what kind of motors copy machines have in them now. There was four motors in that copy machine, I still have two, I gave one away and only one quit working. Most of the time I would leave them turning for eight hours or more. Now that I have bragged on my little motors they will probably give up. Pat