Amazon with Barley Ears has the 2-Pack of Barley Ears 8" Stainless Steel Folding Shelf Brackets w/ Install Screws for $16 - 20% off coupon (check "Apply coupon" box) - $3.20 off with coupon code 15KAMXMO [Exp 5/31] = $10 with free shipping on $25+ or with Prime. 

Max load of 110 pounds. Same code works on the other sizes (prices range from $10 to $23 after code).