how many are you looking to duplicate? Pricing on stuff like that is often unit based, and if you're only talking about 40-50 it could be further ahead buying a small dedicated burner
Also keep in mind the difference between "duplication" and "replication." "Duplication" is burning to DVD-Rs. "Replication" is pressing from glass masters, which is what commercial production is.
DVD Inserts Printed (I know its for 1,000, but I can get them double sided full color and flip it for two projects...only $80 + S&H) http://gotprint.net/g/uploadDVDPackage.do