You don't say if you are looking for 6x4.5, 6x6, 6x7 or 6x9 negative size. If all you want is a MF roll-film camera that can be axccurately focussed, Chinese Seagull, Rolleicord, Yashica-Mat and others do a nice quality 6x6 TLR that can be bought second hand for up to $200 (starting below $100) on eBay but buy only from a seller with good f/b and lots of photoselling experience - like me!
There are nice coupled-rangefinder focus folding cameras from Zeiss - the Super Ikontas are gorgeous!, russian copies of these - Mockbas and Iskras, Agfa do the increasing rare Super Isolettes, Super Baldax from Baldi. The Zeisses are in all three formats - no 6x7.
There are Russian and East German 6x6 SLRs branded as Pentacons, Kievs, Zenit 80, Exakta.
Some uncoupled Rangefinder folders include Mess Baldix, Mess Ikonta, Agfa Isolette lll. From Britain's Ensign company, the Autorange, Commando and Special ranges. Some of these now fetch skyhigh prices! Cheap but very useable are the British 6x6 Agifolds - noting that earlier ones are not all rangefinders,
You can buy a Russian Lubitel TLR with idiosyncratic focussing for about $30 in GWO.
Don't be conned into buying anything sold as Holga, Lomography or Diana. There are nice quality cameras made in China but not these!
If you see anything you are thinking about feel free to message me wiith a link. What I know I share.