Personally, I see no advantage to not using a buyer’s agent. The seller is paying his/her commission. Unless you have at least a little experience in purchasing/owning real estate I would recommend using a broker.
Don’t rely on a broker to negotiate a better price. That depends on you. But, what they can be good at it identifying the specific concessions you may have to make to get a deal, as well as keeping tabs on all aspects of the deal to ensure that you close.
Sure, you can theoretically save 3% on a purchase, but in my opinion one cannot determine the appropriate price for a property to within 3% (nmaybe even 5% in most cases). So, it’s effectively in the noise.