You might wnat to keep an eye out for officemax sales. They keep selling the Cendyne DVD-R/RW drive for around $150 after rebates. The Cendyne drive is just a relabled Pioneer. The latest one is the 105/A05 model. Mine works perfectly in G4/450. Do watch out, Cendyne does have a new DVD+R/+RW drive, which is not the superdrive, and will not work.
Brian