I know you asked for flea markets in Columbus but if you want to stop on the way, you could drive through Amherst, OH (Located 1/2 mile west of Rt. 58 on Rt. 113), and go to Jamie's Flea Market (open Wed. and Sat).
I used to live a couple miles away and my husband would regularly disappear there with his eyes glazed over...lol.
http://www.jamiesfleamarket.com/index.html
Or on Rt 75 (south of Toledo and just north of Findlay OH) there's a nice one.
Unfortunately I don't know of any in Columbus itself at the moment.