If, by, "good idea," do you mean something that I would recommend or even do myself? Not on a bet.
First off, the economics aren't on my side - I'm still going to pay 96, 97, 98% or so for the home even if I get a commission reduction, which isn't a sure thing. Secondly, knowledgeable real estate agents have actual value, and probably nowhere as much as with buying NYC co-ops.
Number three, much of the value a real estate agent / broker has is in education; they should know more about the buildings than you can ever find out without living there, and they can guide you before you commit to a purchase.
Having lived in NYC for over thirty years, it's no place to be without a guide - whether in real estate, or as a tourist.
So, no, I wouldn't put it under the heading of, "Good Ideas."
All the best,