If you're a fan of fine art, shop at Costco. Seriously. The retailer is now selling fine art on its website. Costco says it keeps the cost lower than most galleries by charging no more than a 14% markup. This is actually Costco's second attempt to be a fine art dealer. New York Times explains Costco did this before in 2006, but quit when questions were raised about the authenticity of two Picasso drawings it had sold online. Costco says each piece comes with a Certificate of Authenticity.