I have thought about it and I was actually going to build my own custom vivarium (it was going to be 4ft long and 6ft high and house 3 pythons and 4 corn snakes). However, I'm moving at the end of the month and ideally need something set up for when my animals get all moved in around August 10th. I'm just afraid that I won't have the time to actually build one (as much as I want to) while I'm trying to finish up summer school, graduate, and move. Purchasing a premade rack saves me a little time. I'm willing to pay the extra for convenience simply because I'd rather have it set up by the time my snakes arrive so I'm not stressing them by moving their enclosures all the time.
And yes, I plan on purchasing 2, one for the pythons and one for the corns due to temp differences.