You're getting it totally backwards here. The supplier commission is how much of the card's value BriansClub is paying to the supplier: "On average, BriansClub

You're getting it totally backwards here. The supplier commission is how much of the card's value BriansClub is paying to the supplier: "On average, BriansClub paid suppliers commissions ranging from 50-60 percent of the total value of the cards sold." High demand + low supply of these cards means that the suppliers are getting a better "price" when selling them to BriansClub, the middleman.