A Place in the Sun via eBay offers the Luxton Men's Modern Slim Fit Button Down Dress Shirt in 15 colors (Lemon pictured) for $14.96 with free shipping. (Webzom via Amazon charges the same with free shipping for Prime members.) That's $35 off list and the lowest total price we could find. It's available in sizes 14/14.5 to 18 with 32/33 to 36/37 sleeves, although not in all size/sleeve length/color combinations.
Knowing what to expect in advance can help you prepare for -- and adjust to -- life in your golden years.