I don't have a whole lot of experience to be able to add to this, but I did build my own rack and like Roux, I regret not buying one in the first place. It's mainly that I don't have the tools necessary to really build a nice rack, nor do I trust myself with wiring flexwatt.

If it interests you, my current plan is to get two racks from Animal Plastics, a hatchling rack, and a combo juvenile/adult rack. Not sure how tall, but my current rack is 5 shelves, so maybe about that height. I'm a little annoyed that I've already bought a bunch of Sterilite tubs and that I'm going to have to replace them all with the Container Store tubs that fit the AP racks, but I like how clean the racks look, and that they are stackable. Also, thinking I will be getting a Herpstat 2 to run both racks at once. An incubator is the next thing on the list. Again, I'm nervous about my ability to build one so I might be saving up to buy a small one.

Anyway, that's just my plan, I look forward to an expert chiming in here.