Just got off the phone with the FSC.
Geez, gotta agree...their membership fee structure is a bit confusing to say the least
Apparenly, if you have a parent company you operate under (not necessarily a corporation, but a business entity)...the annual fees are based on annual revenue...not $300/site.
In my case, turns out I paid too much at $300...even though I own 60+ domains. And yes, she offered to process a refund for the difference.