Yard sales can also be a boon when looking for big glass - just remember to clean thoroughly ( a lot of the time folks will let stuff go unbelievably cheap just because it looks so mungy).
We use tupperware for some of ours too, and theres great info on the site for doing that - case-by-case preference.
Yep, gotta go with Smulkin on the yard sale......little bit of bleach will do wonders to a neglected tank. I also have seen quite a few in second hand stores like saint vincent's and goodwill. Happy hunting!
I'm gonna have to pull a David here (Lou Evil) and say that if inexpensive housing is on your list a Rubbermaid or Sterlite system might be best for you! They hold heat and humidity very well, and while not really appealing to the eye they do make your snake very happy! For cheap housing go with sterelite or rubbermaid IMO. If you live in a humid place though and looks are important a tank may work for you - it just is a struggle sometimes to keep heat and humidity up. A good place to look also is like PetSmart they carry All-Glass Aquariums I think = and those are pretty good bang for your buck. IMO though, the best housing for snakes is either a rubbermaid or sterelite or a vision, neodesha or my fav Animal Plastics (those last three are PRICEY though) I'd say best bet for a cheap aquarium is a herp/fish show or any pet store that specializes in fish- they generally charge a bit less for tanks and bit more for supplies (in my experience)... being that you dn't plan on using it for fish could be a pretty good deal for you.
If you really want glass rather than plastic, and don't have the time or the patience to scour the garage sales and other second-hand sources...you can get relatively inexpensive glass tanks at the petstores. Just be sure to ask for "Critter Keepers" rather than aquariums. Aquariums use much heavier glass and seals to support the weight of the water they must hold, and therefore are much more expensive. "Critter Keepers" look just like them, but aren't as heavy and you can't fill them with water. Much cheaper alternative to aquariums.