The Screen printing kit would probably not work without special ink and A UV curing system. I was a bit concerned that they do not list the price on the site.
The Screen printers is a good idea, I've called a few and emailed more with no success yet.
International Plastics is very close. They have a low-volume (100 min as of now) 4 color (full) process printing .. basically eliminating the creation of printing plates (1 per color per side) that is one of the big hurdles to get over. The only downside for me (heck, maybe it will be an upside) is the bags cannot be clear. For my prototype purposes a decent tradeoff.
Here's a link to their specific pagehttp://www.interplas.com/custom-trade-show-bags
Thanks for the pointers,