Apple iMac 5K Retina 27" Desktop - 4.2GHz Quad-Core i7 - 8GB RAM - 2.12TB Fusion Drive - AMD Radeon Pro 580 (8GB) - (2017) - Silver - Best Deal in Town
How to upgrade the 27-inch 5K iMac (2019) with a massive 128GB of RAM [Video] - 9to5Mac
Amazon.com: OWC 32GB (2 x 16GB) PC19200 DDR4 2400MHz SO-DIMMs Memory Compatible with Mac Mini (Late 2018), 27" and 21.5" iMac (Mid 2017), and Compatible PCs (OWC2400DDR4S32P) : Everything Else
Memory Upgrades for 2017 iMac 27-Inch
8GB (2 x 4GB kit) OEM RAM Memory for Apple iMac Retina 5K 27 inch (Late 2014) Core i5 / i7 PC3-12800 DDR3-1600MHz 204-Pin SoDimm at Amazon.com