The ones I have I purchased off ebay. I kept looking for 'mouse lab tub', 'rodent breeding tub', 'lab cages'.
I had to buy a couple thousand dollars worth at once to get a decent price. They aren't cheap, but, quality items rarely are
I have no experience with Rodent Breeder Cages from Critter-Cages.
Instead of going "all in" on one tub type, maybe TRY it for a bit first, to see if your rats chew it?