Yep, the camera on the bay looks nice but the price is out of control. KEH has one in "EX" condition right now for $889, and one in "BGN" condition for $725. I just bought a (I hope) nice RF645 kit w/65mm for a good price, but don't have it in hand yet. Going rate seems to be somewhere in the $650-$850 range w/65mm. I'm saving pennies for a 45mm lens for mine now, which will probably cost me as much as the entire original kit. I've never tried 6x4.5 but finally couldn't stand lugging my 7-pound 6x6 SLR around and sold it to buy an RF645. Plus, I just like RF cameras in general. If I want to shoot larger than 6x4.5 I'll just hang a rollfilm back on my Super Speed Graphic, and still be a couple of pounds under the weight of my previous 6x6 SLR--and have some movements to play with to boot.
I looked hard at Mamiya 7/7II, but the plasticy build and the silly prices scared me off so I stuck with good 'ol Bronica, although I'm sure the Mamiyas have a bit sharper lenses.