Call around to local pet stores if you haven't already, a surprising number have frozen feeders.

http://www.lllreptile.com
http://www.bigcheeserodents.com/
You can order bags of 50 from these folks...not MUCH better, I know, but it's something....and LLLReptile has FANTASTIC customer service.

Hrm...I really wish I could be more helpful on this one, but most of the places I'm finding sell them in bulk.