Integral 16GB (2x 8GB) 1600MHz DDR3 DIMM PC Memory Module Kit US$111.99 | MyMemory
Raspberry Pi 4 8GB
Raspberry Pi 4 Kit 2GB 4GB 8GB Ram Official Power Supply Case HDMI Heatsink | eBay
Amazon.com: GeeekPi Raspberry Pi 4 8GB Starter Kit - 64GB Edition, Raspberry Pi 4 Case with PWM Fan, Raspberry Pi 18W 5V 3.6A Power Supply with ON/Off Switch, HDMI Cables for Raspberry