The Manhattan fleas are fading fast. What does that mean for all the bin-prowling, painting-flipping, chair-testing rummagers with nothing to do on a Sunday morning? Starting April 6, it means riding the C train to a high-school parking lot (specifically, Bishop Loughlin Memorial High School, 357 Clermont Ave., nr. Lafayette Ave., Fort Greene; brooklynflea.com), where a new market called Brooklyn Flea is starting. It will have about 200 vendors, ranging from tried-and-testeds like Olde Good Things to new names that have never sold retail before. Because it’s curated, the vendors are uniformly interesting and dedicated, and the treasures—like this Prague Kolektiv early-seventies Czech cocktail cart ($750, or negotiable)—are in beautiful condition. Bargaining is, of course, encouraged.