Don't worry too much about the acetone & MEK damaging the fabric. It just softens the surface of the plastic a little. Once it evaporates everything is fine. Acetone & MEK are the solvents used in most vinyl adhesives, so no escaping them. Look at the ingredients in the cement tube supplied by Hobie with the patch kit or accessories, for example.
If you go nuts & leave an MEK soaked rag on the fabric for a while then rub the crap out of the fabric, yeah you may damage the fabric. If you just rub normally you'll notice a little color on the cloth you use to clean the PVC fabric. That's okay.
There's quite a few videos showing how to repair vinyl boats. Look at the NRS or Sailrite websites for example. Check out this website: http://www.yostwerks.com
. It has tons of useful info on working with PVC fabric for kayak building.
BTW: If you want a cheap source for small amounts of acetone/MEK solvent look for PVC pipe CLEANER (NOT primer or cement) at your local hardware store in the plumbing section. The small tins are the perfect size for a small job. Look at the ingredients as they can vary from batch to batch. You should be able to find ones that are an acetone/MEK mix with no other solvents. Make sure it has no color added!