Don't get a 180 gallon glass tank. Those things weigh a ton and trying to heat something like and keep humidity will be a nightmare. Plus I would imagine it wont be cheap. Not sure which PVC cage companies you checked out but some can be very expensive. Personally the best bang for the buck I saw were from Animal Plastics, Boaphile or Constrictors NW(Pro-Line) when Ed starts doing cages again next month. A nice size 4' cage with a shelf should run you around $300-$400 depending which company you use but something that size should last you unless you got a girl and she ends up being a very big girl.