MacBook Pro Retina (Mid 2012): SSD Replacement - YouTube
Amazon.com: Odyson - 768GB SSD Replacement for MacBook Pro 13" A1425 & 15" A1398 (2012, Early 2013) : Electronics
Amazon.com: MCE Technologies 1TB Internal SSD Flash Upgrade for MacBook Pro Retina (Mid 2012 - Early 2013) - Includes USB 3.0 Enclosure for Original Drive & Install Kit! : Electronics