After my Pentax sat around on a web page for a year, I sold my 6x7 with handle and lens for $300 to a dealer.
Kiev's and Pentacons can quickly run that up in repairs.
I have seen 500C's for literally free, old style back, but you will need a lens.
Mamiya 1000s occasionally are very low, especially with the plain prism.
Do not buy it without a prism unless you are very creative.
I used to sell a few refurb Pentacons, I like the cameras very much, along with the Kiev version, but reliability is often an issue and am not sure of service here, I sent mine with a friend to Prague and it always came back with a small bag of parts.
Prism, IMO, on them is too heavy.
Spend a little more, buy the Pentax 6x7, a 500C Blad, or settle for the 1000s -- a guy came in more than once to a camera show and sold a Mamiya super outfit with three lenses, case and spare back for $500, so if you really try to squeeze the budget, you may end up penny wise and pound foolish.
Nothing I have not done before, I still have Flexarets I will not sell until I could find reasonable cost cla's for them, would give them away first, some designs just seem to be better than others.
If it is kind of an exercise, then a lot of luck may be involved, but the time is right now, people are selling, and it is a buyer's market here in the US.
Dealers are offering $125 for good lenses, and I sold my Pentax for $300-- the handle was probably worth $100 not long ago.
Stuff happens, yesterday I did see a 60's Dodge Dart a guy found while in Arizona, very clean, one owner, new good paint, clean chrome, at least a 9 out of ten, with a green interior that was so ugly it looked good-- he talked the guy down from $500 to $400 and drove it back to Ohio.
J