I got a FREE 2013 iMac 21.5 with internal upgrades including Samsung evo ssd and 16gigs of ram. Then used open legacy patcher to install Mac OS Venture 13.5 beta. : r/OSXBeta
Install memory in an iMac - Apple Support
2012 21.5-Inch Apple iMac Review: Slim, Sleek, And Stylish, But Far From Shallow | TechCrunch
Memory upgrade: Apple iMac 2012/2013/2014 (Howto)
How to Upgrade iMac RAM: 2012-2022: EveryMac.com
21.5" iMac Has No User-Upgradable RAM; 27" Has Four Accessible RAM Slots - MacRumors
HOW I UPGRADED MY iMAC 21.5in Late 2013 MODEL (SSD & RAM UPGRADE) - YouTube
16GB Memory Upgrade Kit for 2012-2013 iMac 21.5-Inch
Pre-Owned Apple iMac 21.5-inch Desktop "Core i5" 2.9 (Late 2013) 8GB Memory 1TB HDD ME087LL/A - Best Buy
Memory Upgrades for iMac 21.5-Inch 2012 - Late 2013
Apple's New 21.5 Inch iMac Has Upgradeable Parts — That's a Huge Deal