ShopHydra via Amazon offers this 5.11 Tactical Men's AR Sketch Logo T-Shirt in Black for $13.95 with free shipping. That's $5 off list and the lowest total price we could find. It's available in sizes M to XXL.
A close price: LA Police Gear offers it in White, Black, or Tan for $9.49 plus $5.49 for shipping via coupon code "NRA". It's available in sizes S to XXL, although not in all size/color combinations.