Today picked up a $20 2011 iMac 27” with working gpu too! : r/mac
Install memory in an iMac - Apple Support
Apple iMac 3.0Ghz Core 2 Duo 21.5-Inch (Late-2009) *No HDD/RAM* – MSU Surplus Store
iMac 21.5" Mid 2011 How To Change/Upgrade Your Ram For Better Performance 2014 - YouTube
Install memory in an iMac - Apple Support
Timetec 32GB KIT(4x8GB) Compatible for Apple DDR3L 1600MHz PC3L-12800 CL11 for iMac (Mid 2011, Late 2012, Late 2013, Late 2014 Retina 5K, Mid 2015 Retina 5K) SODIMM Memory Module MAC RAM Upgrade at Amazon.com