If price is the only factor, 1/8" ACM is going to be hard to beat. It's relatively cheap, very durable, and cuts well on the CNC at a reasonable speed. It also can come in different colors or can be painted via traditional methods.
There are sign shops in West Virginia. They have to get their material somehow. 4x8 sheets of ACM is one of the most common materials in the sign industry at this point. I'd be shocked if there wasn't a cost effective way to get it to you.
If you want an idea on wholesale pricing, PM me and I'll give you the 4x8 pricing. I don't like to share wholesale pricing on public forums.