This year's annual Hollywood Prop & Art Auction claims to be offering the prop of Luke Skywalker's severed hand from The Empire Strikes Back. But you've got to read the fine print. It turns out this is not Luke's severed hand (which was his right hand) but a sculpt of his left hand:
This piece was created by Stewart Freeborn (creator of Yoda) who was in-charge of make-up and special creature design on the film. It was the original piece created for the final battle until George Lucas decided it should be Luke's right hand. This is the casting of Mark Hamil's [sic] left hand holding the hilt of his lightsaber.
So it's a bit of a scam. If you're still interested, follow the link. Bids close 30 March 2013.
(via ComicBook.com, who did not read the fine print)