Walmart offers the RoomMates Star Wars Episodes 1-3 Peel & Stick Wall Decals for $11.46. (Sears and Home Depot match this price with in-store pickup. Amazon charges the same with free shipping for Prime members.) Opt for in-store pickup to dodge the $4.97 shipping charge. That's the lowest price we could find by $3, excluding the mention below. It includes Obi-Wan, Anakin, Darth Maul, the droids, and more.
A close price: Target offers it for $12.59 with free shipping via coupon code "TURKEYDAY".