I just picked up the Plextor 708A for $220 its a dual format that does 8x dvd+r, 4x dvd-r, 4x dvd+rw, 4x dvd-rw as well as being a 40x24x40 CD burner and I think you can find it cheaper.
They also have good deals on DVD+ or -R discs....you can get them about a buck apiece and buy package deals for DVDx express 25 dvd+/-r discs, some other software and 10 dvd holders for $50.
Check
www.newegg.com or
www.tigerdirect.com