Used 2017 Apple iMac 27" Core i5 3.5GHz 24GB RAM 1TB Fusion MNEA2LL/A - Walmart.com
Memory Upgrades for 2017 iMac 27-Inch
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
Install memory in an iMac - Apple Support
Apple iMac with Retina 5K Display (2017) review | Digital Trends
Apple iMac 27-Inch with 5K Display Review (2017): Serious Power | Tom's Guide