Well, I'm no expert, at least not yet, but you'll need a vacuum table to hold the paper still when you print and some specially made transfer paper. Union Ink has a good article on it and also sells the paper and some really good opaque inks specially formulated for transfers.
Union Ink Company | Screen Printing Inks
I have been using their paper also, but I'm told AceTransCo makes the best, so I'm going to try that next.
Transfer Express makes really nice transfers, but unless you are buying a lot, it is a pretty expensive way to go. I love the fact that I can now make my own (at least on a good day). I have found humidity and paper shrinkage to be my nemesis, but that's only with 2 or more color designs.
If you aren't up to the task, you should advertise for the service on the classifieds. I met a couple of guys in Baltimore this past weekend who also make their own and I wouldn't be surprised if you could buy them locally from another screen printer for less than TE sells.