A-Tech 4GB RAM for Apple MacBook Pro (Early/Late 2011), iMac (Mid 2010, Mid 2011, Late 2011), Mac Mini (Mid 2011) | DDR3 1333MHz PC3-10600 204-Pin SODIMM Memory Upgrade Module at Amazon.com
I recently purchased 2011 21.5 iMac (Mid-2011) and I'm obsessed. : r/mac
Apple A1311 iMac Computer 21.5 in Core 2 Duo 3.06 GHz 8GB RAM 500GB HD Late 2009 | RecycledGoods.com
16GB Kit 4x 4GB DDR3 SODIMM RAM 1333MHz For Apple iMac 2011 12,1 12,2 Memory RAM | eBay
A-Tech 4GB RAM for Apple MacBook Pro (Early/Late 2011), iMac (Mid 2010, Mid 2011, Late 2011), Mac Mini (Mid 2011) | DDR3 1333MHz PC3-10600 204-Pin SODIMM Memory Upgrade Module at Amazon.com
Apple iMac (spring 2011) review: Apple iMac (spring 2011) - CNET
Memory Upgrades for Apple iMac 2011 Up to 32GB
Apple iMac 2011 - 21.5 inch - Core i5 - 4GB RAM - 500GB HDD – PCMaster Pro