Derek, I'm the one said binding your carpet scraps was the answer to every
floor-covering need.  It's one of those things that doesn't have an "official
cost", so you either negotiate in round $5 increments, or with a show of 
reluctance agree to buy their carpet remnant if they will bind it when you
bring it back cut to fit.  The carpet store has a sewing machine that does it;
inside corners are the only part that's remotely tricky for them.  It'll take
them about 7 minutes total to do all the mats you've got.

Thanks for your summary.  If I went with JCWhitney, I would probably work my
way up from cheapest, figuring that if I don't like the sisal or whatever,
I can either send it back or use it in rotten weather.
B.