Discmakers (the first name I sort of recognized in a quick Google search) has an on-line automatic quote system for short run duplication. I just ran it for 300 copies, no cases, no inserts, black text on the DVDs and got back $1.39 per DVD + shipping. They have a lot of standard options (inserts, cases, etc).
I've never needed to make a bunch of DVDs, but I've at least heard of these guys before, and their web site indicates they do want to do business with small runs like this.
I just did a quick search for bulk DVDs and found one price of about $0.60 per disc (for 300), plus shipping (DVD-Rs - I don't know what brands are good, that one was just cheap). So at the quoted rate from Diskmakers, you would be paying $0.79 per DVD for duplication and printing on the disc surface. That would give you a nicer finish than hand-duplicated DVDs, and eliminate the time and trouble of doing it yourself.
The only downside would be that you'd have to come up with the $417 + shipping all at once instead of being able to duplicate one at a time as needed. Diskmakers does do smaller lots, and at only 100 discs, the same job is just $1.49 per disc.
Basically, for small runs, doing it yourself probably can't be the most cost effective way, unless the size of your run needs to be on the order of 5 or 10 discs. At the hundreds of discs level, you probably want to leave the work to someone with the right gear for the job.