Any idea how much a system like this would cost?

http://www.animalcaresystems.com/optimice.shtml

I was thinking of breeding mice for ferrets (I don't have any now, but I want some) and after a little math, I discovered I would need about a hundred mice for only few ferrets, and, well, that would be a lot of sterilite bins.
Anyone know, or even have an educated guess?

Way too much. You'd be better off building one yourself. I think someone just recently posted something about building rodent racks. I'd suggest doing a search for rodent rack building and see if it is within your capabilities to make one, or maybe you could find someone who help you.

But, seriously, do you have any idea? I like to give my mice a lot of room, and it would cost $313 (just for the bins and wire on top) to build a rig capable of as many mice as a 100 cage one will hold.

I don't know about those you talked about but if you want to buy a rack, these ones seems better. And the prices are on the site.

Good luck.

http://www.themouseemporium.com/options.html