Well, if you consider getting the .info domains, www.APLUS.net has them for 49 cents, there is a limit though. I wouldn't understand why you would want 100 domains at one time, but there are a few reasons I could think of. It's just a little odd how you want them all at the same time. Anyways, there are some good sites that can help you get a large ammount of domains for a good price, .com's, .net's, and .org's.
I would never use aplus for anything. Horror! In fact I would use GD before I used aplus.
Seriously, with 100 domains to buy and manage I would do it with eNom. With that many domains somebody would probably give you a $7.95 reseller account. If that wasn't an option maybe Directi has become better since I left them.