Give him his little thrill as long as you get what you want. Money is not as important as the product; I've been scammed all my life and it's on them not me.
So you might lose out one day, maybe soon even but it hardly matters - imagine what it takes to deal. Fuck that. This is not a friendship. Play along. I'd even feed it for fun ...or just get your drugs and run.
Greed is everywhere; dealers are attracted to low-effort, high-profit transactions. Many of them are not businessmen and think "it's illegal anyway so I can fuck people around - they have no legal recourse". Sad fuckers, stupid fuckers whose life problems compound day by day and they wonder why (?),
Play his silly game. As long as you get what you want.The value is in accurate product representation and purity.
He will think of it as building trust. Tell him about the last guy that scammed you - the one at the bottom of some hole, far away.
Play those fuckers or do nought.