If you are sew inclined, you can make your own.
Cut 2 7" squares of cotton. Press down 1" on top of each.
Cut 1 6" piece of sew on velcro and align across the 1" of cotton you pressed down.
Stitch close the both long edges of the velcro and repeat for other piece of cotton.
Put 2 pieces cotton right sides together and stitch using a 1/2" seam allowance, turning at bottom corners to sew along three edges of bag.
Clip corners, turn, press and think you are wicked cool.
Don't feel sew inclined. Visit fourcorners to buy yours...buy one get one this week. Oilcloth are listed, but cotton will be posted later today. Share a bunch.