Yes, when you quote the buyer, always include your fee in it.
The Fee Agreement which I have given you states that you will discuss the fee by email or skype or Whatsapp.
That way, you can have different fees for different buyers for the same product under the same agreement.
Before you let them get on with it together, just tell the supplier and clarify your position…
Your price to me is xxx and my price to the buyer is yyy. This makes my commission zzz per ton.
So please remember my commission amount and if you do decide to give him a discount, keep my commission amount intact.
After he agrees…
I will connect you with the buyer now so you can convince him directly.