The ARS racks are very nice, and the prices you quoted seem decent (assuming they come with all of the tubs and t-stat), but they are geared toward the big league breeders. That said, if you're fairly certain about the numbers you're thinking of (20-ish) it may not be a bad idea. There comes a point where you have to balance your DIY skill level against the value of your time spent elsewhere. If you're a skilled builder and it's going to take you 4 hours to build your own, then go for it. This kind of project would take me days, and I wouldn't be surprised if I glued or nailed my hand to the rack, so I would just buy the ARS rack because it's cheaper than going to the hospital to stitch up a nail hole.