16GB 4x 4GB Memory Ram For Apple iMac 21.5-in & 27-in Late 2009 - Walmart.com
Apple iMac 27" Late 2009 i7-860 2.8GHz 16 GB RAM, 240GB SSD, Radeon HD 6970M 1GB | eBay
A-Tech 16GB Kit (2x8GB) DDR3 1066MHz / 1067MHz PC3-8500 SODIMM RAM for Apple MacBook (13 inch, Mid 2010), MacBook Pro (13 inch, Mid 2010), iMac (27 inch, Late 2009), Mac Mini (Mid 2010) at Amazon.com
27" Apple iMac 3.06GHz Core2Duo 2TB HD 16GB RAM (2009) - MacUnited
Apple iMac 27" 3.06GHZ (2009) review | TechRadar
Apple iMac Late 2009 All in One Pc i7 16gb Ram 2TB HHD 2.8gz Selling as Is | eBay
Timetec 16GB KIT(4x4GB) Compatible for Apple DDR3 1067MHz / 1066MHz PC3-8500 CL7 Dual Rank for iMac (Late 2009 21.5-inch / 27-inch) SODIMM Memory MAC RAM Upgrade for iMac 10,1 and iMac 11,1 at Amazon.com
Late 2009, 27 inch iMac can use 32 GB of 1333 MHz RAM, beyond what Apple says - YouTube