So, when I received my Ikea catalog a month and a half ago, I saw an awesome item in the storage section. To me, it looked exactly like a snake rack. It was inexpensive ($40 for the rack, $2 each for the tubs), so I decided to see what it was like. My aunt was going near an Ikea and I asked her to pick up a unit for me.
All I have to do to set up the rack to house snakes is put a back on it to keep heat in (such as foam sheet insulation or tileboard) and run a strip of flexwatt.
The tubs have lids (unfortunately I didn't get enough - just had my aunt get 3 so I wouldn't waste money on a useless lid since I wasn't going in person to see them before buying) and are great because they fit flush into a recess in the bin. There is about an inch round hole in the lid (meant to be a fingerhole to pull the lid off) which needs to have some hardware cloth riveted over it or something, but it is a good opening for putting a thermostat probe.
The tubs are awesome - very heavy, translucent, rounded with no sharp corners on the inside, and with a nice groove that spilled fluid could collect in (and keep the rest of the surface drier).
I just have to make minor modification to each tub, putting cheap "turn buttons" on each corner of each tub (these are those little swivelly buttons that are on the back of nicer photo frames, that you turn to get the back off the photo frame to put your photo in), which when swivelled over the lid, will prevent the lid from being pushed off or moving at all. Do a search for "turn buttons" on Google or on Rockler.com to see what these things look like. I will post photos when I get some and install some on a tub.
Here's the rack (minus backing insulation and flexwatt):

Here's the inside of a bin:

Here's a bin with the lid:

Closeup of the corner of a bin with a lid:

Closeup of the drawer slides (which are plastic):

And a lid by itself:

It was very easy to assemble.
Here's a link to the bins:
IKEA | home | Children's IKEA | Children's storage | Children's organizers | TROFAST Storage box - select Transparent and 16 1/2" x 11 3/4" x 4" for size and color. $2.00 each (the rack I got holds 6).
Link to the shorter rack unit (the one pictured here):
IKEA | home | Children's IKEA | Children's series | Furniture series | TROFAST series | TROFAST Frame - $39.99
There is a taller straight unit as well, and also some shorter stepped-style ones.
Link to the lids for the bins:
IKEA | home | Clothes storage | Children's storage | Children's organizers | TROFAST Lid $1.50 each
Ikea is still a bit weird with online ordering - even just for lids, the shipping is outrageous, so it's best if you live near an Ikea to just go to the store and buy everything there, but for a total of about $61 plus a few bucks more for heating and insulation and some minor modification to the lids, not bad for a juvenile rack.
The lid fits completely flush into a recess in the bin, which is why those little turn buttons would be able to keep the lid on.
