First of all, apart from one 1950s Agfa "Clack" Medium Format P&S, I do not own any mf cameras myself, but I've been looking into the cheap MF camera market for a while 
Basically, there are three types of "cheapo" MF cameras:
- Eastern German cameras.
These include the Pentacon Six, Exakta and several more. There is a wide range of available relatively high quality lenses for these, namely Zeiss Jena, Schneider Kreuznach etc. Consider these cameras to be on the high end of "not-so-expensive" MF cameras - a former workmate of mine owns a Pentacon 6 and is really happy with it.
- Former USSR cameras,
namely the Киев (Kiew) 60 and 88. The Киев 60 is a copy of the Pentacon Six, the Киев 88 is a Hasselblad imitation. Both are alternatively available with the Pentacon mount (instead of M42), so you can use the high quality lenses available for the DDR made cameras. The Киев models suffer from very poor quality control - and with "very poor" I *mean* "very poor". Expect the advance handle to jam sometimes, which can be fixed by repeatedly bashing the camera against a hard surface. This is soviet camera technology - the user should be able to fix it with very crude tools 
Some importers offer refurbished cameras with adjusted mechanics and calibrated light meters (don't expect this to be done by the factory) which make for quite good cameras, though to a little bit higher price, of course.
- Chinese cameras
The probably most known brand here is Seagull, which manufactures several kinds of TLR cameras. Lenses are non-changeable, but the more expensive ones apparently use copies of German lens designs.
All in all, you can get a refurbished Киев camera with a decent set of lenses for about 500 USD, which is quite a good kit price, IMO
Just don't expect too much of it, there is a reason why a Hasselblad body costs so much more money.