I have no idea what would sell. But it occurred to me, that maybe something that hasn't been done (much), like a shirt that looks like a hi-vis vest, or a like a popular fictional character's outfit, long forgotten. I'm picky with prints, I wouldn't go for either lol! The shirts I used to buy, were of fictional beers, promotional shirts for odd companies or events.
You could make a fake promotional shirt, or find an old company that died and left no forwarding address... there's so many old companies and products to choose from.
devilsgarage
That sailor moon t-shirt is pretty sweet! https://www.teepublic.com/show/30279-sailor-moon
LovelyKouga
Thank you! ^^
It's too bad it shows up so small/far away on the tshirt site, you can get a better look here: http://fav.me/d7ju0yk