I'm selling all my Canon gear so the extender must go. It's a great extender which I have used extensively with the Canon 135mm f2L with outstanding results. The extender has two tiny spots in the coating on the front element (in the perimiter) that do not affect the pictures taken with the extender. Consequently I have set the starting bid at only $100.
Please check the auction
here. PM me with any questions. I have a 100% rating on eBay so you can bid with confidence.