Proozy offers a selection of Under Armour men's T-shirts from $12.99. Coupon code "DN4" takes an extra $4 off, dropping starting prices to $8.99. Plus, all orders receive free shipping. A couple of best bets, with prices after coupon:

Under Armour Men's Heatgear Big Logo T-Shirt for $10.99 (pictured, $14 off)

Under Armour Men's USA Jet T-Shirt for $10.99 (low by $11)