Must be small rack at that price.
My rack holds 6 rat bins and 24 mice bins, wood, screen, screws and tubs came out to 200$ as tubs arent cheap when your buying that many at 3$ a pop for mice sized and 4.99 for rat ones.
this rack used 20 8ft 2x2s at $5.59 per 4 pack
If you dont want a huge rack you can stick with tubs. I used 70-100qt tubs for rats once and it held 5 females and their litters nicely.