Best bet is the Pioneer DVR-107D. It costs $123 at NewEgg.com. And if you order it, make sure you check out their combo specials - you can get five free DVD-Rs or a free T-shirt with your order. The link to their special deals is at the lower left corner of their front page.
A cheaper option is the NEC ND-2500A, which is only $90 shipped right now. However, this drive is not natively compatible with OS X - you have to use some drivers LaCie wrote in order to get burning in Finder, iTunes, Disk Utility, etc. I wouldn't count on it being iDVD compatible.