It doesnt work that way, the listing agent does not reduce their price if there is no buyer broker as now they have to do twice the work. That is like you going to work, having another worker to help you with all your days tasks and then the next day your boss gives you twice the work and says you have no helper today and by the way we are going to pay you half of your salary today.
A buyer broker does not cost the buyer anything. Where you havent signed anything that agent is not working for you, they have to be fair and just but without you hiring them, there are things they can not do for you by law. A buyer can negotiate the buyer broker contract so that it does not cost you anything out of pocket as the buyert broker gets paid at closing through the fee offered by the listing agent in MLS. The buyer agents job is to look out for you and assist you through each step of the buying process. They can offer you comparables to know what the house you want is worth in todays market. They can then assist you in negotiating for it.
Good Luck with your purchase.