I have the NEC 3520a... that and the NEC 3540 are pretty much the ultimate budget DVD burners, IMO...
they burn every format out there (CD-R, CD-RW, DVD-R, DVD+R, DVD-RW, DVD+RW, DVD DL +R), and will support newer formats (DVD DL -R) with firmware updates.
they are also plenty fast and don't seem to care about what media I stick in it, as even the cheapest crap is burned flawlessly (such as the 25 pack of 8x DVD+R I got for $8 at CC).
They range in price from $35 - $45, but are sold OEM - that is, no IDE ribbon, no software. If you're on a budget though, you just can't pass these up
If you have more money to spend, you should probably look at Plextor or Pioneer, although I don't have any experience with them.