I also can't comment on the prices for those racks, but I too made my own. All materials for the rack an the heat tape and thermostat (a VE-300X, might be wrong on the number, working off memory, but it is the "upgraded" 300) came out to about $400. I have 7 slots that can fit 2 tubs side by side, so a total of 14 tubs can fit. Currently only have 6 snakes, so only 3 slots filled.
I may or may not breed in the future, all of my snakes are babies. I did get snakes that would work toward my goal if I did decide to breed them down the line. For now I'm just enjoying them for what they are, watching them grow up, and learning all I can about the genetics behind different morphs, as well as what it takes to breed them. I probably wouldn't be able to breed anything until next year.