The concept of bundling in MTR and sending out more material is interesting, but the pricing seems off. I can order 6 T-Shirts with the same logo online using the highest-quality t-shirts and ink for about 23$ and then shipping is about 10$. I also found a few places offering Ethereum-branded wear online around the same price point (Not counting any value on the MTR you plan to throw in on the deal).

My concern would be that any success would be short-lived since others can easily emulate, the local T-Shirt shop down the street will do a one color full t-shirt print front and back for about 15$. It also stands to take your focus away from Toshidesk and MTR unless you have help to handle this part if it does take off.