One common argument for buyer's brokers is that they don't cost the buyer anything: the seller pays for their commission. If I were buying a $1M apartment, the seller would pay $30,000 (3%) of that to my broker.
Alternatively, I could not use a broker and instead negotiate the price I pay to $970k (basically what I ended up doing, though it's hard to definitively say what I would've paid had I used a broker).
One could argue that a broker's experience could more than pay for the fee, but I have a hard time believing this is true 90%+ of the time (which is how often buyers hire brokers).
It was pretty easy (and enjoyable, at least for me) to research what was on the market thanks to aggregators like StreetEasy and major brokers' own websites (I'll also concede that I may have missed out on some off-market listings, but was able to find a place I love in spite of that; this may be somewhat different in a seller's market, but I don't know). I arranged showings directly with the listing broker, researched what to look for in an apartment and what questions to ask, and often brought experienced friends and family to these apartments.
My particular experience was perhaps unique because I ended up buying a condo in a new development with an experienced developer (but I don't think it would've been particularly costly or hard to hire a home inspector myself), but I was still able to provide comps, write a persuasive offer letter, research the developer, and negotiate closing costs. I ended up paying 7% under ask and paying no transfer taxes, and I really doubt I'd have gotten more than 4.5% under ask had I used a broker.
My strategy may be too risky for many others -- this was my first home purchase, after all -- but I did a bunch of research, reached out to friends and family for advice, and consulted an attorney before submitting any offers.
I ended up spending a bunch of my own time doing work that someone more experienced could have done for me, but it was a great learning experience and seems to have had a huge return on investment.
If you're not willing to try this strategy, I recommend looking for brokers who will agree to some sort of commission rebate. In NYC in particular, a company called [Prevu](https://www.wework.com/creator/personal-profiles/real-estate...) offers a two-thirds rebate (note: I have no affiliation with this company and never used their service, but some of their [blog posts](https://www.prevu.com/blog) were quite helpful to me).