I think the price points should be adjusted a little bit. Very few people are going to want to pay more than $30 for a shirt. This means that for almost all of the shirts, 3/4ths of them will never sell. It kind of looks bad.
Its not as catchy, but $10 + (Shirt Number/4) seems like a better formula- $10-$35.
Its not as catchy, but $10 + (Shirt Number/4) seems like a better formula- $10-$35.