AVOID Crafts stores if at all possible ...Just TOO Expensive.!!! May have to "drive into town" to find a good fabric store ....

You could get together and purchase canvas together (Co-op) saving a trip ... best "let your fingers do the walking "... Phone around ... see if they even carry canvas..
You know , there are many other fabrics that might do the job too ... I was thinking about that aircraft Dacron , which you can brush/spray the special glue on the skin , let it dry and then Iron on the fabric to the foam (fuses to the foam ) ... and it shrinks tight as you iron ... More expensive than T2 and canvas, but gives a finished look/surface , and actually cuts with pinking shears... easy to paint... Just another possibility ... Not thrifty per se, just different ...
Jury Duty .... grrrrr!!!! Civil or Criminal?