I run my rats in racks with the mortar tubs or in 16 quart Sterilite tubs for my maternity rack. I have no idea on cages or how well they work or don't; never used them, cost and convenience being the two deciding factors there. The Bean Farm sells them as well if you're closer to the West Coast so as to save on shipping costs:

http://beanfarm.com/index.php?cPath=1233_1234