My next website will be 100% white shirts with some viral potential. We're working on the code now and the premise is you can get free shirts if you can get enough of your friends to "cheer you on" when you're about to add an item to the cart. All you have to do is share a link to the shirt (personalize link) and your friends will see your shirt and you'll have a "chat box" for them to cheer you on. The idea is to get people partying when they buy, and maybe get their friends to jump in and try to earn a free/discounted shirt, too.
My average cost of goods sold on a white tee is now under $1.92 including shirt, labor and ink costing. What's the harm in giving away a $2 costed tee if it brings 30-50 people to the site to cheer their friend on to making the purchase?