I work at a sign shop, and we've done screen printing, we also have a partner in town that is setup to do massive tshirt screen printing. Honestly if you guys do a group buy you can probably get 20 shirts or so done for under 10 bucks a pop.
Wholesale black tshirts are like 1 or 2 bucks.
Burning a screen 2 sides is probably 20 bucks per side.. Our partner doesn't even charge us.
And the swiping the ink would take a skilled screen printer maybe 30 mintues to do. Our shop did 1500 swipes in 2 days and that was our first ever screen printing job.
All you need to do is talk to a local tshirt screen printer and ask them what they need. They will appreciate if you can provide them with a vector image.
Heck if someone wants to start a group buy I can give em some advice, I know a few screen printers in the bay area.