what the heck do you need a FULL tower case for? You can only fit 2 hard drives, a floppy, and 2 cd drives off of any standard motherboard (unless you have a ton of add-in expantion cards)...
Pricewatch.com is a good start.
I'd also look at techsunny.com as well. got my last case from there at a steal.
But I just consider a nice mid-tower...which is PLENTY room. I still have 3 bays open after two hd and 2 cd's and a floppy...