Ebay is a good bet for cannibalized parts. In addition, there used to be a company that carried parts for them but I can't recall the name - do a Google search on Unimat and it may come up. They are good small lathes - worth fixing.
Ebay is a good source and you might also try www.sherline.com, as I believe that they make some accessories for the Unimat as well. They are cute little lathes and $180 is a good price, just be prepared to spend some doe for the accessories, you'll probably spend quite a bit more than you did for the lathe tooling it up, but that's the way of the machine tool world.