I have a Pioneer DVR-K04 Superdrive sent to me by apple as a replacement for the crappy Matsushita drive in my Powerbook, but decided to upgrade to a MBP due to the time the drive took to arrive (10 days!)
Since it's brand new I think £30.00 plus £8.00 for CityLink P&P is resonable.
Cheers,
James Grant
P.S, feel free to check my ebay feedback (wildman150_0)