I usually go to boutique vintage shops that are not very easy to find and are unique and one of a kind. However, I had to finally visit The RealReal. Even though it's a huge franchise, they do have an amazing luxury vintage selection to fit all of your vintage needs. They have locations in Chicago, LA, and NYC.
From The RealReal
"The RealReal is the world’s largest online marketplace for authenticated, resale luxury goods, with more than 30 million members. Buy & Sell bags, jewelry, and clothing from designers like Chanel, Gucci, Louis Vuitton, and Prada."
66 E Walton St, Chicago, IL 60611