From: John Foust <jfoust(a)threedee.com>

And although eBay appears to be doing nothing with all that pricing information of all their past auctions, you never know.

On the other hand, I bet that if you published a price guide in any market and directly noted that you derived your price info from eBay auctions, they'd smack you with legal paper urging you to cease and desist from mining their property without permission.