I think it was at the Beachland Ballroom in the Flats - (the rock n roll flea market). I don't know that it was an actual "flea market" but I think it was part of some guy's tour... but I could be thinking of something else. My husband used to book DIY bands in our area and he remembers someone sending a press kit that was titled "Zombos rock n roll flea market".
I have to agree with the bring your table and set up yourself with free parking idea... that is if you don't want to go the club route or something. There is a craft fair in Kent (Kent State) annually that is held at a local park. It is in the middle of summer with a rain date and it is primarily dominated by jewelry and metals people from Kent State, although there are cooks, glass blowers, flame swallowers and the like in attendance as well. It is a community thing, but it is an outdoor venue that is really relaxed. I know of sevaral parks in the Cleveland area as well as the Columbus area that would provide a similar venue.
Those would also be the people I would kind of look for interest in as well... the crafts majors at universities. Although Ohio can be cool I don't know anyone who knits "vibrator cozies" although maybe I am hanging with the wrong crowd!
I typed Chicago before but I meant Detroit... although I have never been there, I just saw Detroit Rock City ~ ha! ha!