Can you block print? Also remember the background colour will affect any colour you put on top of it, I think fabric painting only works proprly if done on a really light ground, and you would have to do each one individually, whereas screen printing you can do them all the same and quite fast ( I would only stick to one colour though)
I think computr transfer is your best bet tbh, for a professional finish
how about slick writers - dylon do a range too - they are a 3d liquid paint a bit like writing icing would be a good way to describe it!! You don't need to fix it either so a lot less faffing about - but you will need to practice first it takes a while to get the hang of it.