How to Upgrade iMac RAM (21.5" and 27" Aluminum): EveryMac.com
Apple iMac mi-2010 21.5" Intel Core i3 - 3.06 Ghz - Ram 8 Go - SSD 1 To | Rakuten
Timetec Hynix IC 8GB KIT(2x4GB) Compatible for Apple DDR3 1333MHz PC3-10600 for Early/Late 2011 13/15/17 inch MacBook Pro, Mid 2010 Mid/Late 2011 21.5/27 inch iMac, Mid 2011 Mac Mini Laptop Memory - Newegg.com
Apple iMac 3.0Ghz Core 2 Duo 21.5-Inch (Late-2009) *No HDD/RAM* – MSU Surplus Store
Apple iMac 27" - Mid 2010 Reviews, Pros and Cons | TechSpot
A-Tech 8GB RAM for Apple MacBook Pro (Early/Late 2011), iMac (Mid 2010 27 inch 4-Core, Mid 2011 21.5/27 inch), Mac Mini (Mid 2011) | DDR3 1333MHz PC3-10600 204-Pin SODIMM Memory Upgrade Module at Amazon.com