8GB 2 X4GB Memory for iMac 27" inch 3.2GHz Quad Core Intel Core i5 Late 2013 ME088LL/A 1600MHz DDR3 (PC3-12800) SO-DIMMs RAM (PARTS-QUICK Brand) at Amazon.com
Apple iMac A1311 21.5" (May, 2011) 20GB DDR3 RAM i5 2nd Gen CPU 512 GB SSD | eBay
NEMIX RAM 16GB Kit (2x8GB Upgrade) DDR3-1600 SODIMM PC3-12800 for Apple MacBook Pro Mid 2012 / iMac Late 2012 / iMac 2013, Late 2014, Mid 2015, Mac Mini Late 2012 at Amazon.com
16GB 2 x 8GB 1866 1867 MHz PC3-14900 Memory RAM for Late 2015 APPLE iMac 5K 17,1 | eBay