I found a new product called soft and stable (byannie.com) This a wonderful product that I used in my Selvage tote. I'm totally sold on it and will continue to use it. I had a hard stifner in this bag until I attended the Sew Expo this year and discovered the product. Annie's purses and totes look very professional and beautiful. Take a look at my last tote made with soft and stable. I did find it at my large local fabric store-Fabric Depot in Portland, OR. The wholesale department will pull it off the floor and ship it to you but byannie.com will too and she is one lovely lady I would like to continue to support!
For the support in the bottom of my totes I also use a piece of coroplast board. It's strong and I cut it so the corraguated lines will go across for more support not lengthwise. It's plastic so if it gets wet it doesn't get ruined or give. I use this product to wrap my yardage of fabrics on. It's very strong so it will hold some weight. I cover it with a piece of lining and top stitch closed at one end.
http://www.quiltingboard.com/picture...e-t183290.html