32GB (4X8GB) Memory Ram Compatible with Apple iMac Core I7 3.4 27-Inch (Late 2012) by CMS A6 at Amazon.com
A-Tech 16GB (2x8GB) PC3-12800 DDR3 1600MHz RAM for Apple MacBook Pro (Mid 2012), iMac (Late 2012, Early/Late 2013, Late 2014, Mid 2015), Mac Mini (Late 2012) | 204-Pin SODIMM Memory Upgrade Kit at Amazon.com
Parity > imac late 2012 ram, Up to 69% OFF
Review: 21.5-inch 2012 iMac takes two steps forward, one step back | Ars Technica
Memory Upgrades for iMac 27-Inch (2012 - Mid 2015)
Can you upgrade the RAM in the 27-inch iMac? | iMore
Apple iMac A1418 21.5" Desktop - MD093LL/A (November, 2012) for sale online | eBay
Apple's 27" iMac Late 2012 model. How to upgrade the ram to 16GB - YouTube