Walmart offers the Munchkin Auto Seat Protector, model no. 27306, for $7.45. (Amazon charges the same for Prime members with free shipping.) Opt for in-store pickup to avoid the $4.97 shipping fee. That's tied with our February mention and the lowest price we've seen. (It's a current best by $5.) It features a non-skid surface, storage pocket, and stabilizing wedge.