Thousands of holiday shoppers are coming to buy used kids' clothes and toys at 50-90% off the original prices at one of the largest pop-up garage sales in the world. It’s housed inside a 50,000-square-foot former Sears store outside Philadelphia. Sarah Herrmann, a mom of three, snagged a Calvin Klein jacket for her son for just $17. Marissa Stinson was able to purchase a Patagonia bunting for just $12.