I understand that you are selling T-shirts, but why not silicone bands? They're cheap as F*** to mass produce and would turn profit after about 4 sales of £3/$5 Easily for a total of buying about 100 stock, Anything after that would be pure profit!
It seems like a good idea, My mate goes to gigs and sells them (without permission) and sells them £5, tax free (Lets just say it pays for his ticket & travel, plus he has a little bit to go home with!)
I've looked around, and these guys look pretty cheap:> here <
I would certainly buy one if it comes in a dark looking colour, + they're alot cheaper to make than t-shirts and easier to sell.
I dunno what the admins think about this but I thought it might be a good way to fill the coffers, and if it works out you can send me one of those snazzy new t-shirt designs you have