Just south of Austin is a small town called Kyle. If not for the huge billboard "Flea Market", you'd miss the market and the town!
Just drive slow and turn off at the next exit. A dirt frontage road will wrap you around to the grass field where you'll find vendors selling yard sale items like vhs tapes, toys, books etc. on wooden tables. Once you've greeted everyone and rummage through a few boxes head into the warehouse for the real vintage picks.
I found most of the merchandise to be over priced but there was so much to look at. Take these beer cans packaged to sell...
My daughter had a great time looking for barbies and toys. I rather liked people watching and viewing the tiny rooms filled from top to bottom with stuff. We quenched our thirst with a a soda and walked the hallways peeking into each room hoping to find a hidden relic. At the end of the venture, we ended up with a bag of cheetos and a few pics! I don't think I would plan a day trip around this flea market, but if you are driving to or from Austin, it's worth stopping by for kicks.