I'm sort of in the market for an 01R/W. Does anyone have any ideas what the market value is, assuming I can find one?
Thanks in advance!

I've found that the going price hovers around $800. 01/Wfds are running from $1200-$1300 on average, so $800 for just the brain is a rational deal. Just be aware that the module lacks a disk drive (card slot only)and has only the same 7,000-note sequencer that the 01/W keyboard proper has; that is, you lose your sequence when its turned off, so make sure you use it in conjunction with an 01/Wfd or PC sequencer to save your work.
As far as FINDING one of the little wonders goes, I've been treated well by ugbm.com (Used Gear By Mail) and roguemusic.com. They offer a rational guarantee (90 days +/-) that a tech has made sure the box will do the appropriate tangos you buy 'em for.
I strongly recommend checking out Keyboard magazine in general for all kinds of useful info. Their URL is keyboardmag.com, which includes their classifieds section. That'll give you access to most of the 2nd-hand outlets. Hotcha!