If storage units in your area Jes are like stores with proper lighting and power available then that would be my choice. Of course you need to consider rental fees, traffic, business licence, your time and any other costs and regulations involved that would effect your return. I think if set up properly within a high traffic area you could maybe do well. Of course you may not know if it's profitable until your second or third season. Like anything, there's no guarantee. As for flea markets, if they are anything like the ones here then I'd steer away. A lot to consider when setting up shop away from home.