Amazon.com: Vemico Raspberry Pi 4 Model B 4GB Set RAM 4GB Base Starter Kit with SD Card, Heatsinks, HDMI Cable, Power Supply, Black Case, Reading Card Device, Screwdriver : Everything Else
Raspberry Pi 4 B: How Much RAM Do You Really Need? | Tom's Hardware
Assembled Gertboard GPIO Expansion Board For Raspberry Pi
The Raspberry Pi 4 gets a RAM upgrade: The 2GB version is now $35 | Ars Technica
Amazon.com: GeeekPi Raspberry Pi Set-top Box Kit,Raspberry Pi 4 Extension Board with 4010 Fan 5V (Blue LED Light) + Raspberry Pi 4 Heatsinks for Raspberry Pi 4 Model B : Electronics
Raspberry Pi 4, Enclosures & Cameras | Newark
Raspberry Pi Pico GPIO Expansion Board
Raspberry Pi 400 Gets an 8GB Upgrade — By Hand-Balling and Soldering a Donor RAM Chip - Hackster.io
I made the Raspberry Pi 4 with 3GB of RAM. : r/raspberry_pi