I got these from Wes at The Snake Hut. This is a new cage he is marketing. The actual product will not be exactly like this but you get the idea. I bought his proto-types and made some modifications to them to fit my needs. He can fit a 4 ft X 2 ft X 18" cage in a box 6 or 7 inches thick and ship for around $15 per cage. They come in about six pieces all predrilled and very easy to assemble. Definately worth a look. I'm not sure on his pricing but I think I saw him run some ads for under $200 shipped.
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<img src=http://gallery.pethobbyist.com/data/731cage4ft-med.jpg>
They have them in white and black. I cut these down to 12" high for Rainbow breeding cages. The rainbow in the pic is 3 1/2 ft for size reference.