I have a 36 tub 6 qt rack.  It is taking up room and it needs to go.  I got it in a trade and don't need it.  The tubs are tight in some and a little loose in some.  I wouldn't put baby colubrids in some of them but any of the bigger babies would be fine.  You can always shim the tubs up a bit too.  There are 36 tubs that cost a buck or so each and casters on it.  I am letting it go for $50. Thats about what the tubs and casters would cost.