Bought a mid 2010 iMac at goodwill for 15$. It works technically.... : r/mac
Identify your iMac model - Apple Support
Amazon.com: Timetec 16GB KIT(2x8GB) Compatible for Apple DDR3 1333MHz PC3-10600 CL9 for Mac Book Pro (Early/Late 2011 13/15/17 inch), iMac(Mid 2010, Mid/Late 2011 21.5/27 inch), Mac Mini(Mid 2011) MAC RAM Upgrade :
Apple iMac Core i3 4GB Computers | MC508LL/A | Discount-Computer.com
Apple iMac 21.5" Mid 2010 Intel Core i3 8GB RAM 500GB HDD AMD Radeon High Sierra | eBay