I saw that same shelving unit at Lowes and had the idea to turn it into a series of cages using plywood attached to the frame. It was just the right dimensions at 36x18.
But, since it was $75, I decided to just build the whole cage unit out of ply and save some money.

As for a rack, did you consider building one yourself out of plywood? I did my rack like that and it works wonderfully. TONS cheaper than any premade: @$40 for the wood, $15 or so for the hardware, and $20 for the paint...more or less.