Barry - I've picked up various types of quilted (etc) material from fabric stores in order to make my own wingbags in hte past, and it always bugged me that the material was so ridiculously expensive.

When I was looking for protection for my Hunter wings, I stumbled across a pretty cheap alternative - headliner material, as used in trucks etc. This stuff is 1/4" foam with a material lining on one side, and can be used single width, or doubled up to 1/2" foam with material lining on both sides. I'm not talking about a headliner kit that comes precut for a given vehicle, but instead a roll of 50 ft or more that you can simply cut your desired shapes from.

I forget where I bought mine, but a few minutes with google / bizrate etc ought to find you several sources.