I have asked about flea markets in the past, and was provided with this link:
New York City Flea Markets
but I'm thinking some of these listings may be outdated.
Anyways, I always check the calendar outside of PS 69 in Jackson Heights because they do list some local events, and they used to advertise a flea market. I haven't seen one advertised or actually taking place for a long time, but
this past Monday (President's Day) I happened to walk by one taking place between 78th and 76th street on 37th Avenue.
I walked around a bit to see if I could find a person that looked to be in charge, but I couldn't find anyone that fit the character-type. I left the area, tired from supermarket journeys, and vowed to ask on City-Data and do some other research online.
Years ago, someone provided me with a contact for this flea market, but I recall reaching out to them and never having anyone get back to me.
Any assistance on this matter would be appreciated. Thanks.