I got mine brand spankin' new from Music 123 for $400.
They had advertised an "open box" RM4 for that price, but when my wife called to order it, the open box unit was no longer available. However, because
a) they had failed to take down the $400 open box ad, and
b) my wife is a master at bitching at customer service reps,
she got me a brand new unit at the open box price!
You might want to call some of the big mail order chains and ask if they have any open box/demo units at reduced prices. They should still come with the full warranty. Better yet, for a small fee, I'll rent out my wife to do the calling for you. (um, just kidding)