A lot of real estate agents don't use offices any more, or perhaps they borrow one for the closing ceremonies. Indeed you can negotiate. As I noted, here in the bay area the houses cost 3 times as much as 15 years ago, and the realtors are not working 3 times as hard or doing 1/3 the volume because of it. When I bought in 1991 my realtor worked plenty hard for 1/3 of what they get today.

I think it's better to buy services a la carte. The negotiating/closing services (from the realtor, escrow service, title company and sometimes lawyer and surveyor) are pretty standard (though escrow and title insurance can be based on cost.)

During the boom, the "marketing" effort of a listing agent was trivial. List the house, run an open house. Many people come through on Sunday. Bids arrived tuesday, buyer selected (all bidding over asking) by end of the week. That time is over but boy were the agents making a killing then. Anybody can put you in MLS, but I presume that buyer's agents steer their buyers away from houses listing a low commission for them, or, if they are being monopolistic, from houses not sold by pals in the monopoly.

However, so far nobody has managed to use the internet to break that monopoly. Companies like zip face opposition wherever they go.