Apple 21.5" iMac Late 2012 - Catalina, 1TB HDD, Intel i5 2.9GHz, 8GB RAM | eBay
Memory Upgrades for iMac 27-Inch (2012 - Mid 2015)
Apple 21.5" Pre-Owned iMac Desktop Intel Core i5 2.7GHz 8GB Memory 1TB HDD (2012) Silver MD093LL/A - Best Buy
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
A-Tech 8GB RAM for Apple MacBook Pro (Mid 2012), iMac (Late 2012, Early/Late 2013, Late 2014, Mid 2015), Mac Mini (Late 2012) | DDR3 1600MHz PC3-12800 SODIMM 204-Pin Memory Upgrade at Amazon.com
Apple iMac "Core i5" 2.7 21.5-Inch (Late 2012), 1 TB HD, 8GB RAM, OS 10.11.6 - Imagine41