Jo-Ann's Fabric typically has 40% off sales on fleece! If you have one in your area, definately sign up for emails, coupons, etc. Even when they don't have a sale, every week I'm getting flyers in the mail for 40% off one item which will count towards one yard of fabric
For my sturdiness I use (2) panels of fleece. Usually a print with matching solid. Depends on sales. When they have 50% sales, that's when you need to stock up! You can get the solids as cheap as $2-$3/yd! That's only few times a year.
I sew my own straps in and they are double-thick, stitched around edges, then placed into hammie for attaching. They barely give. Some of my hobs (in tact ferrets weigh as much as 5-6.5lbs and the hammies don't give much.) This works nice for my chinkin who is a feather in comparison!
Metal shower curtain hooks, get a bag at Lowes, HomeDepot, or hardware store for under $2! (typically in hardware aisle, not in bathroom shower area like you'd expect!..go figure