Shopping cart covers..

My LO is 6 month old today and just got a convertible seat so no more infant seat.. I usually wear her anyways but sometimes we get hot and she sit in the cart. She tries to put her mouth on everything so I don't trust just wiping it down.. She also will rest her head alittle when she's sleepy. I've just been using a blanket so far. All the ones I've found in stores are $25 plus and that seems pricey to me for a shopping cover. Anyone know of a shopping cart cover for like $15?