Do a search for "wolf" or "Noah" car covers. They are the same material as the california car covers. Also try searching for a more common car,like a chevy or ford that is the same basic dimmensions.
I did this with the car cover for my 68 T/C wagon. It was going to cost more then $500 for a custom cut cover for the wagon. After some research I found that a newer ford excursion was very close, so I bought a wolf car cover for $150 and it fit pretty well. Little tight in a few areas and obviously not a perfect fit, but keeps the car protected and I saved $350!!