Having your design used for an awesome band's last shirt? I would be content with that.
Announcing a "winner" implies that you're winning something. the way its worded to me sounds like YOU are so lucky that we picked your shirt and are going to make money off of it. Doesn't seem right.
If I were a real graphic artist I would see this and run. But I'm not. I'm a fan who dabbles in graphic design from time to time and enjoys it. I'll probably take a stab at it. But it does seem sort of... cheap.
But then again, I can't tell you how often I look at band t-shirts and think how ugly they are. Now I get a chance to correct that.