With patience you may be able to find a Mamiya 7 with lens for under $800. I found one with the 80mm lens I was looking for for $500 by watching ebay. I needed to adjust the range finder, but I now have a spare body. The big limitation to me was the close focusing distance with the 150mm lens. It's really not a great system for portraits. But as a walk around landscape camera I love it.
However, I think as a general use camera the Hasselblad is the way to go. I have tried the RZ, Mamiya 7, Mamiya 645, various folders and TLRs. I am keeping the Hasselblad and the Mamiya 7 since I use them in very different ways. If asked to choose one, I think it would be the Hassy.
Of course my Mamiya 645 kit is for sale, so really that's what you should buy Actually it is very nice, and I hate to sell it.