Original Penguin has Select Men's Button-Up Shirts on sale for $40 - 50% off with coupon code PENGUIN50 in cart - 20% off w/s stackable code OFFEROP20 + $0 shipping [Exp 10/29] = $16 shipped. Includes this P55 Plaid Shirt for $16 shipped w/ codes (select "Bright White" to see more sizes in stock).

Some are even less, but sizes are very limited.