I picked up a hauler the day before yesterday. When I saw how simple they are, I immediately priced out the necessary materials at Outdoor Wilderness Fabrics.
http://www.owfinc.com/
It would cost about $5 to make your own. If you need more than 2 or so, it would be well Worth making. The sewing needed is so simple that anyone could make it with just a few pointers on using the sewing machine.