I'm looking at MF cameras and I'm sort of overwhelmed and confused about which one would be the best choice for me. I shoot 35mm but i'm sort of getting bored of the format ... I've held one MF camera before and i really liked the feel and the look and the machinery (and I don't need to mention the size advantage of negs).
My budget is around $300-350, I'm looking at SLRs. I don't need AF or AE, or anything automated for that matter, hopefully that should drive the price down. I have a slight preference towards 645 format, being the cameras are generally more compact and cheaper, but I'm also willing to use 6x6. I don't think a 6x7 camera would be right for me because I've read that they're bulky and expensive. I would prefer interchangeable backs (and rotating back, if they make those in 645), but beggars can't be choosers.

I saw a Mamiya M645 kit at my local camera shop (I'm not sure about everything included in the kit) for $250. I might buy that camera, but I've read reviews saying that its difficult/cumbersome to shoot vertical photos (rotating back would help with this). Also, it does not have a removable back.

I've heard good things about Bronicas, Hassys are probably (definitely) way out of my league.

Or am I simply asking too much?

I have a terrible attention span, researching things (even cameras) doesn't really agree with me, should I expect to get at least one "suck it up and do your own research" reply?