64GB RAM upgrade kit for 21.5-inch iMAC now offered by OWC - 9to5Mac
Apple A Grade Desktop Computer 27-inch iMac A1419 2017 MNEA2LL/A 3.5 GHz Core i5 (I5-7600) 48GB RAM 4TB HDD Storage Mac OS Include Keyboard and Mouse - Walmart.com
OWC Confirms 64GB of RAM in Apple 27" iMac 2017
How to upgrade RAM in the (Mid 2017) 5K iMac and save up to ~$900 [Video] - 9to5Mac