Tanga offers the Art3d 6-Square Foot Peel and Stick Brick Wall Panel for $18.99 with free shipping. That's a buck under our May mention and the lowest price we could find by $1. They feature a self-adhesive substrate.
Buying 20 or more? Art3d via Amazon offers a 20-Pack for $379 with free shipping. That scores a slightly lower per-unit price of $18.95. (Samples are also available for $4.99 with a $25 purchase.)