I've done a bunch of conversions, including a Univega Supersport. It's a nice riding generic Japanese mid-level frame. If you like bike projects and the creative aspect of building your own fixed gear, go for it. Cost wise it's less expensive than new, though if you don't have tools you may need to spend $100 bucks or so on that. The most expensive bike I've done added up to 500 bucks, only because I put a carbon fork, seatpost, and nice wheels on it. Also, you're recycling instead of feeding some Chinese factory and faceless Internet business!