I have two ARS racks, one has the birthing tubs:
http://arscaging.com/ars5032.html
The other has the grow out tubs:
http://arscaging.com/ars7024.html
The good thing about ARS is that you can buy just one level at a time. Or you can just buy the tubs and build your own. I chose a shorter stack with fewer levels because a full stack wouldn't fit in my basement because of the low ceilings. When I just started out my first stack was just a few levels, basically what I could afford at the time. Once my operation grows I'm planning on getting a spare rack so I can power wash the dirty ones.