Think he means PPAI, it's a membership association similar to ASI/SGIA/ARA, basically an association where you sign up and get vendor discounts and trade show access to some events as well as instructional access. PPAI and ASI seemed to always go hand in hand in my experience and primarily benefits pad printers and people looking to outsource pad printing (for products like printed pens, buttons, etc).
Even if you join PPAI I don't know if you'd get the skills/education you need. What you're attempting is like the cut and sew of Hats. I imagine if you can find a decent tailor/seamstress class it would cover most things you need to know.
If you're dealing in bulk, then finding a company overseas might be the better and more profitable way, but if you're going to limited designer run type of marketing, then it may be worth your while to learn.