Sure. Zippers are fairly standard, and come in a set number of sizes.
Try a local boat top place - they can stitch things up too, and it's usually pretty inexpensive. You can also call our customer support team and ask for the number to BD Company. They aren't related to us, but they stock all sorts of fabrics and zippers and stuff like that for our products. 800-845-3567. (I'm at home, and don't have BD's number here).