Street Moda via eBay offers the Company 81 Men's Dri-Fit Combat Performance T-Shirt in five colors (Blue pictured) for $8.99 with free shipping. That's $23 off list and the lowest total price we could find. It comes in sizes S to L XL, although not in all size/color combinations.
Jos. A. Bank cuts up to 79% off a selection of its men's underwear and T-shirts. Shipping starts at $5.95, but orders of $50 or more qualify for free shipping. Size availability for some items is limited. A couple of best bets:
Tillys offers the Blue Crown Men's Contrast Pocket Tank Top in four colors (Charcoal pictured) for $14.99. Add two to your cart to drop the price to $20. Coupon code "FS2015" bags free shipping. That's $10 off and the lowest total price we could find. It's available in sizes S to XXL.