Yugster offers the Colorado Timberline Men's Worthington Polo Shirt in seven colors (Navy Blue pictured) for $9.97 with free shipping. (DirectDeals4U via Amazon and NetDirect Sales via eBay both have it in nine colors for about the same.) That's $20 off list and the lowest total price we could find. It's available in sizes XS to L (and XL in Black), although not in all size/color combinations.
Of note, it's also available in big & tall sizes in four colors for $11.97 with free shipping. That's the best deal we could find by a buck. It comes in select sizes from XL to 5XL, although not in all size/color combinations.