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.