You know, I just saw one on ebay, which was advertised as new & in original packaging, for $421.
If you already are into M-mount lenses, the GXR-M is a really great thing, and I don't think an extra hundred dollars or so should deter you. It's a lot less than M lenses cost--even old moldy ones--and this way you can have an extra lens mounted on a body, ready to shoot. I might add that in some ways the GXR-M is a very modern machine with some nice features. Some are M-lens-specific, like the lens corrections you can put in and the special sensor. Others are modern things like scene modes you can play with.
Tom