Amazon has rolls of webbing - 1 inch wide, 25 yards, for about $8. I bought this one for making tote bag handles and it seems to be the same quality as webbing I've bought from Joann's:
http://www.amazon.com/gp/product/B00...ls_o02_s00_i00
My idea (when I get around to it!) is to run a stripe of ribbon down the middle to match the bag. I have a lot of ribbon on hand that I need to use up.