We've found for the 41-qt and larger racks it's much cheaper to DIY than to buy them online as shipping is a killer. The other alternative is to scour your local FB snake/reptile groups and CL for other people selling theirs. Obviously you'd need a truck - or a friend with a truck - to go get it since many sellers can't or won't deliver. I've scored some incredible deals on 4' to 8' long commercial enclosures just by being willing to drive an hour or so... or with the eight footers, having a flatbed trailer available.
I put up a thread in the DIY section on a 9 tub BP breeder rack. I'm just not sure about how tall the tubs could be. I would def build one. Buying usually costs about $75-100 per tub, building costs about $35 per tub.