Does anybody know approximately how many yards it takes to do a canvas? My canvas is okay I guess with a few tears and the zippers don't close, but it will eventually need to be replaced and I can't pay $1000+ to buy one. I was thinking if I'm still around, I might be able to find somebody local to sew one up, but that depends on the cost of the fabric and the labor. I have other issues to take care of, but it's good to know what the long term costs will be. TIA.