2020 5K iMac RAM Upgrade Guide - Save $2100 on 128GB! - YouTube
Third-Party RAM for 27-inch iMac Still Far More Affordable Than Apple's Checkout Upgrade Options - MacRumors
Adamanta 16GB (1x16GB) Memory Upgrade for 2020 Apple iMac 27" w/Retina 5K Display, 2019 Apple iMac 27" w/Retina 5K Display, 2018 Apple Mac Mini DDR4 2666Mhz PC4-21300 SODIMM 2Rx8 CL19 1.2v DRAM
RAM Door Cover for iMac 27" A1419 (Late 2013, Mid 2017)
Apple 27" iMac® with Retina 5K display (Latest Model) Intel Core i7 (3.8GHz) 8GB Memory 512GB SSD Silver MXWV2LL/A - Best Buy