I am confused by your question since the listing agent is the one who pays the buyers agent. If you are the buyer, you have nothing to negotiate, but if you turn around to sell, that's when you can ask for a slight reduction in commission...however, I explain it like this when I list a house:
I use 6 $1 bills and say these 6 represent the commission you will pay. 3 goes to the buying agent and if I don't offer 3, you will get fewer showings and less opportunity to sell. Out of the 3 I keep, 1 goes to my company, 1 goes to marketing YOUR house and the expense associated with that and the last dollar I rip in half and say, 1/2 goes to Uncle Sam and the other half is what I take home and feed my family with. Now if you want me to cut my commission, which dollar would you like me to remove from the equation? Haha.
So many people think agents make a lot of money, but we don't. If you are the buyer, sit back and let the seller pay your agent's commission. If you are the seller, think about what it's worth for you to sell your property and how hard you want your agent to work.
