Amazon.com: Apple iMac (21.5-inch, 8GB RAM, 1TB Storage) - Previous Model : Electronics
Komputerbay MACMEMORY Apple 4GB Kit (2X 2GB Modules) PC2-5300 667MHz DDR2 SODIMM iMac and MacBook Memory at Amazon.com
Timetec 32GB KIT(2x16GB) Compatible for Apple DDR4 2666MHz / 2667MHz for Mid 2020 iMac (20,1/20,2) / Mid 2019 iMac (19,1) 27-inch w/Retina 5K, Late 2018 Mac Mini (8,1) PC4-21333 /PC4-21300 MAC RAM at Amazon.com
Memory upgrade compatibility list for iMac 2019-2020 | Page 15 | MacRumors Forums
32GB (2 X 16GB) Kit Memory for Apple iMac Late 2015 27-inch 1867MHz DDR3 SO-DIMM at Amazon.com
4GB [2x2GB] DDR2-667 (PC2-5300) RAM Memory Upgrade Kit for The Apple iMac 7,1 (20-inch, 2.0GHz, MA876LL/A) Intel Core 2 Duo (Genuine A-Tech Brand) at Amazon.com
Amazon drops current gen. iMac prices by $125 matching lowest prices ever, now start at $1,175 - 9to5Toys
How to upgrade RAM in the (Mid 2017) 5K iMac and save up to ~$900 [Video] - 9to5Mac