JCPenney offers the Arizona Men's Basic Crewneck T-Shirt in 18 colors (Aquarius pictured) for $5.99. Coupon code "YOUSHOP7" cuts it to $4.79. Opt for $3.95 in-store pickup to dodge the $8.95 shipping fee. That's $7 off list and the lowest price we could find. It's available in sizes XS to XXL.
Of note, it's also available in V-Neck for the same price via the coupon code above.