The advantage for keeping snakes in racks in that you can stack a lot of animals in a minimal amount of space. If you never have more than three snakes, and don't plan on breeding there's really no point. Just use a Rubbermaid or Sterilite tub of the appropriate size with a latching lid. Or if you have some money to invest, a nice PVC cage will give you the better heat and humidity control with the look of a glass tank vivarium.