When I first saw the prices on racks, I was pretty suprised as they appeared expensive to me. SO I can understand how the OP felt. But the more I thought about it and broke it down to cost of housing per snake and what other options cost, it really isn't that bad. This is keeping in mind that I am very frugal and a bargain hunter.

When you pay for a rack the cost goes towards materials, labor/time, craftsmanship/skill, the tools used to build them and the space needed to do so.

If I wanted to build a rack, I would need to buy tools and materials (I don't know tools, so I couldd't even estimate that cost). I don't even know where I would build it as I am in an apartment. Then let us consider craftsmanship/skill. I've put IKEA furniture together wrong. Anyone who builds racks sucessfully has a craft skill I do not possess. Next is time. There are many things I would rather do than build. But saying I tried, I could not even say how long this would take me. I've looked at some of the DIY plans foor a cooler incubator and that seems like more than I want to deal with and from what I have heard they are easy to build. They there is getting materials and all of the driving and gas money that goes into that.

I think if I was a craftsman, had the tools & space and an inexpensive source for materials that building may make sense to me. Especially if I actually liked building things (which I don't). All this taken into consideration, I find that purchasing a rack is preferable. Buying allows me to not have to worry about all those things mentioned above and I can then focus on things I actually enjoy with my time.

Now that being said, the frugal part of me wishes I could make all of these things myself at half the cost.. lol..