Rubbermaid or Sterilite Tubs... Better at holding heat and humidity than a tank and cost anywhere from $2.50 for a 6 Quart tub to MAYBE $20.00 for an adult ball pythons tub. The majority of people with multiple snakes have either racks or tubs. Yeah they don't look that great but they really don't look that bad either. Besides maybe building your own cage that's really the best way to go.
Hell, just buy a rack and fill it up...