If your in the area Laird Plastics south of 696 on Groesbeck has acrylic sheets for sale. They're the cheapest I've found so far. I'm building a sump and that's where I plan on going. I'm just not sure what you will need to handle all of that heat.
I just called them directly (thanks for the link), and they said to either call a distributor, or go to my local hardware store. They said any acrylic will do, which didn't sound right. So I now have 2 questions from this:
1. Does the type or thickness of the acrylic matter for shields? I have 2 Mh bulbs in this unit along with 2 VHO's.
2. Does anyone know of any plastic/acrylic shops closer to Ann Arbor?
The acrylic might not melt but i'm sure it will start curving. The width it is spanning will probably cause it to either bow more or less. Look for plastics on yellow pages.com and check out companies web sites or call them to see if they carry acrylic.