Apple iMac 2.5Ghz i5-2400S (Mid-2011) *No HDD/RAM* – MSU Surplus Store
iMac RAM upgrade: Here's an affordable way to improve multitasking - CNET
Apple iMac 21.5" - QUAD CORE - 8GB RAM - 2TB - THUNDERBOLT - macOS High Sierra | eBay
A-Tech 8GB RAM for Apple MacBook Pro (Early/Late 2011), iMac (Mid 2010 27 inch 4-Core, Mid 2011 21.5/27 inch), Mac Mini (Mid 2011) | DDR3 1333MHz PC3-10600 204-Pin SODIMM Memory Upgrade Module at Amazon.com
A-Tech 32GB (4x8GB) RAM for Apple iMac (Mid 2010 27 inch 4-Core, Mid 2011 21.5/27 inch) | DDR3 1333MHz PC3-10600 204-Pin SODIMM Memory Upgrade Kit at Amazon.com
Memory Upgrades for Apple iMac 2011 Up to 32GB
HOW TO: Upgrade The RAM to 32GB on a Mid-2011 21.5inch iMac - YouTube
Install memory in an iMac - Apple Support
Apple iMac 21.5" FHD All-in-One Computer, Intel Core i5-5250U, 8GB RAM, 1TB HD, Mac OX X 10.11 , Silver, MK142LL/A (Used) - Walmart.com
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