I use sweater boxes (actually plastic shoe boxes) as hibernacula for brumating snakes. They're very convenient for that purpose, but my biggest complaint about them is that you can't see through them very well. Be sure to drill MANY, MANY holes in the sides and lids to provide adequate ventilation. I also use larger plastic boxes to keep snakes that aren't on display (see below). They're functional, but not attractive. Like you mentioned, they're cheap, but I prefer to see as many animals as possible. That's why I prefer glass or Plexiglas enclosures.
Rick
