I had thought of the trust issue. My guess is that this is more a problem with individual faculty than with affiliates. Someone could tell us they charged $100 for a course where they actually charged $500 (so as to send us a smaller amount in dues)!
If we have an online certificate verification scheme, that will offset any malpractice out there. When a person enters their cert number, they should see (1) that it exists, (2) that it corresponds to the course they received and (3) if the cost of the course is published it will help cover situations where the cost quoted to us was different.
I have been working on a database for WGI-Ireland (WGII) and have an approach for the cert numbers.
Coming back to the membership issue, I would suggest a figure of 2.5% rather than the 5% I mentioned in my last post. I believe that figure would be acceptable to members directly and to affiliates. If membership were collected via affiliates they would send the 2.5% (of the reference figure, locally recommended cost of a 30-hour course) to WGI together with a list of the members’ emails. Masaki has already shown that such figures are possible and I’m sure other affiliates would think the same.