Amazon.com: iFixit Battery Compatible with MacBook Pro 13" Unibody (Mid 2009 to Mid 2012) : Electronics
Amazon.com: A1382 Battery for MacBook Pro 15 inch A1286 Early 2011 Late 2011 Mid 2012 New Replacement Laptop Battery (7200mAh 10.95V/78.84Wh 25 Months Warranty) : Electronics
NewerTech® : Batteries : NuPower® Battery for MacBook Pro 15" Unibody Early & Late 2011, Mid-2012 Models