Well, I don't know what fairly cheap is, but the external drives listed
here at my favorite Mac parts place OWC all have FireWire and start at $71.99- and even the lowest price one uses the latest Pioneer drive mechanism (DVR-116D with burn speeds to 20x) that I am using two of in my MacPro.
I would have no hesitation to order that one myself- but would caution you to avoid the many "slimline" externals as few (if any) of them are capable of greater than 8X burns and virtually all are USB 2 only.
One nice thing about a full size drive such as the OWC also is that it a very simple matter to replace the mechanism as future upgrades come out- and standard size drive mechanisms are usually under $30 from either OWC or newegg.com. The same can not be said for slimline drives.