Amazon.com: OWC 16GB (2 x 8GB) PC19200 DDR4 2400MHz SO-DIMMs Memory Compatible with 27" iMac w/Retina 5K (Mid 2017), Mac Mini (Late 2018), and Compatible PCs (OWC2400DDR4S16P) : Everything Else
iMac Pro Memory Maxxer RAM Upgrade Kit
Apple iMac 27" Late 2009 i7-860 2.8GHz 16 GB RAM, 240GB SSD, Radeon HD 6970M 1GB | eBay
Mini-review: Test driving a fully loaded, $4,000 27-inch 5K iMac | Ars Technica
Best Buy: Apple 27" iMac All-in-One Computer 8 GB Memory 1 TB Hard Drive ME089LL/A
Picked up this iMac (27", mid 2011) i7 @ 3.4GHz , 16 gb ram , 256 SSD in excellent condition for $210. Should I make any upgrades ? GPU, bigger SSD? Thanks : r/LukeMianiYouTube
How to Upgrade the RAM in Your iMac | Envato Tuts+
How to upgrade the RAM on the 27-Inch iMac (2020) | AppleInsider