Hello Gents,
I'm in Michigan. The following IMO and based on experiences I've had in my area. When they come up, you can get nice (with normal battle scars) garden variety Ms. Pacs for $500 all day. They don't start out at that price, but the ones I can talk down to that price, I buy. I think that's fair for my area. I've seen them as high as $1000 to $1200 to start, but these are sellers looking for gullible buyers or guys that think that they have something special. I doubt anyone is actually getting that for one.
For $600, it would have to be a pretty nice looking version. By that, I mean, close to being fully restored.