Check out https://jcpromotions.info/calendar/ - they run TONS of Street Fairs and Flea Markets in NJ, and they’re constantly adding more. When I first started checking their website 5+ years ago, they had like 5-10 Fairs they produced. There are DOZENS now.. one almost every weekend during spring, summer and fall. If you tap on the event name/date, there’s a link to register your booth/table and/or contact info if you have questions.

That website is also a great resource for people who are just looking for something to do on a random Saturday or Sunday, too.

Good luck!