This one I got at a Salvation Army store for $.99 because one of the pockets was torn. This bag was made out of the back only, and a free pattern I found on Simplcity.com. It's only two pieces of "fabric" and easy sewing. The challenges came in when I tried to incorporate the snaps for a closure instead of using velcro like they suggested.
You can see where I tried to sew the snaps on, and the bottom line is all crooked from the foot of the sewing machine hitting it. I'll definitely have to work on that, but I have plenty from this one coat (and it's a kids size!) to make a second one.
The kids are already arguing over who gets to use it!