Amazon offers its Prime members the Columbia Men's Perfect Cast Polo Shirt in Collegiate Navy for $9.47 with free shipping. (Non-members can spend $49 to qualify for free shipping; otherwise, shipping costs $5.58.) That's the lowest total price we could find by $21. It's available in sizes XL and XXL only.
Note that some sizes are temporarily out of stock, however they can be ordered at this price and will ship when available.