just thought I'd share my experience on ebay
I recently sold on Ebay my 15" PB G4 which I had purchased in October 2005. I sold it through the Buy It Now option for $1,250.00. It was a fully loaded powerbook and I included an isight camera, and some extra software like ilife 06 and iwork 05 and toast 7.
My only advice is to watch your auction well. I had another auction of mine (another used PC notebook I had) bid spammed by some moron at the end of the auction and it ruined a good auction for me. Fortunately I was able to sell it quickly once I got Ebay to erase that first auction.