I found three Gas Mask bags at an Army/Navy surplus store for $2 each and made panniers from them. I also use a modified briefcase found in a thrift store for $1 as a pannier. I cut the waist and shoulder straps and sewed two 1" X 6" nylon webbing with synching buckles to the bags. The briefcase got grommets installed through the nylon webbing handles and I use mini-clips through them to attach the briefcase to the rack. $13 for an insulated Ascent rack bag from Nashbar is just too easy and cheap to make yourself. Here's my loaded touring bike with bags.