If you know Asbury well, there's also a beachfront parking lot by the old Carousel building. The parking lot is adjacent to one of the Ocean Grove foot bridges, and a five minute walk to the flea. Follow directions to the Empress Hotel to find that lot. It's no longer free, but a couple of bucks to park there may be worth it (it's also the closest lot to the flea, and you'll be able to pop in Bodega, my favorite shore shop, on your way home!).
Good luck, and happy hunting!