Columbia offers its Columbia Men's Trail Shaker Polo Shirt in Purple Sage Heather or Grey Ash Heather for $19.98. Coupon code "COLSEPT70" cuts it to $15.98. Plus, Greater Rewards members receive free shipping. (Not a member? It's free to sign up.) That's tied with last month's mention and the lowest price we could find by $3. It's available in select sizes from S to XXL. Deal ends October 1.