Yeah, I wouldn't even worry about HD or Lowes. They have no clue what to order and they act like they can't get it, even after they tell you they can, or they don't want to go throught the trouble.

Call your local mill shop or cabinet shop. I made all of my new racks and chondro cages from black melamine. It's a little more expensive, but looks very nice. If you have plans figured, I would also have them cut it. Most shops have a CAD program that will make precision cuts by lazer. Melamine is heavy, as I'm sure you are aware, and it's much easier to have them worry about making mistakes. The only think you have to do is attach the edging and assemble. If you need edging that is simple, go to www.rocklerpro.com. You have to order it by 250' roll, but it's relatively inexpensive and you just iron it on.