There are loads on ebay from about £12.00 + P&P maybe even cheaper
all flashed and ready to go.
if you wish to get you own drive and flash it with the fw you need a samsung drive
and the info below is from textbook 2008 so get that down from the stickies and it will tell you all you need to know.
Method 1 – Purchasing a “Kreon” Drive (best option)
The following drives can be purchased, installed in your PC, and then flashed with one of Kreon’s alternate firmwares for reading Xbox 360 games.