Ah, yes. There's no excuse to not hang out at this market. First of all, TI is gorgeous and there's plenty of amazing vendors to check out. Do note, this is more a hybrid craft and antiques fair rather than a flea market, but still great nonetheless. I don't hate the beer and cocktails either.
Cost: $3 admittance, free parking
Photo c/o SF Girl by the Bay + Rachelle Dunn