If the point of businesses using social media is to get you to buy things, then Pretty Penny wins the contest, hands-down. Scrolling through the vintage store’s perfectly peppy Instagram feed — which is maintained by owner Sarah Dunbar — you’ll find pictures of its cute shopgirls and equally adorable customers in various retro fashions, as well as an intense littering of likes, size questions, and even real-life sales in what might be the East Bay’s best use of the photo-sharing app. Become friends with Pretty Penny on Facebook and you’ll find daily photos of new inventory, props to other local businesses, and genuinely loving shout-outs to the store’s customer base. Dunbar also tweets; pins on topics like “Great Hair” and “1940s style”; and Tumbls addictively scrollable photos of more stuff to drool over. To some, this level of sharing may seem like overkill, but to anyone with a little more foresight, Dunbar is clearly an expert businesswoman — bringing her cult of vintage to (many) screens near you.