Acrylic or cheap acetate case for larger/tall figures?

[SpaceCrawler]

I need a case that would cover a larger figure that stands on a base that's about 12 inches square. Acrylic cases are at least $100 each custom made. The dimensions would need to be about 11x11x20 inches (opening in the bottom). Any suggestions on an affordable acrylic case that fits those dimensions or perhaps a source for one of those cheap flexible acrylic dust covers that might come in larger sizes?

Sean