This is particle board. It's wood coated in melamine.
http://i35.photobucket.com/albums/d187/cixelsydmi/hatchlingrack1.jpg
There's the finished rack.
5 12x36" laminated boards. $29.85
2 12x24" laminated boards $9.94
125 1.75" #6 screws $3.49
1 2x6 pegboard $3.53
16 Sterilite shoeboxes $15.84
Project total: $62.65
That makes each individual cage cost $3.91.
Now, I got enough screws to make 3 more cages. I have a TON left over. If you have screws lying around, use them instead of buying some. That's $3.50 saved. And you don't have to buy 16 shoeboxes all at the same time. I bought 4 when I set up the rack, and I already had a bunch lying around.
The only thing I've found that I really don't like about it is that I used Sterilite shoeboxes. A month after I set up the rack, I found Iris shoeboxes for $1.99 each, and I think they're more than worth the price difference. The Iris tubs are about half an inch shorter, but have more floor space (they're rectangular, instead of having the sides slope out, so the floor space is almost as big around as the lid of the Sterilite tubs), and they look a LOT nicer. They're also easier to clean, because of the lack of ridges inside.