A-Tech 8GB Memory RAM for Dell OptiPlex 3020 SFF - DDR3 1600MHz PC3-12800 Non ECC DIMM 2Rx8 1.5V - Single Desktop Upgrade Module (Replacement for A6994446) at Amazon.com
Dell OptiPlex 3020 Micro Mini PC i3-4130T @2.9GHz 8G RAM 128Gb SSD WiFi W/AC | eBay
Dell Optiplex 3020 SFF Intel Core i3-4130 3.40GHz CPU 4GB RAM DVD No HDD No OS | eBay
Amazon.com: Dell OptiPlex 3020-SFF, Intel Core i5-4570 3.2GHZ, 16GB RAM, 512GB SSD Solid State, 4K Support, DVD, WiFi, DP, VGA, Keyboard, Mouse, Windows 10 Pro 64bit - Multi Languages Support (Renewed) : Electronics
Dell Optiplex 3020 SFF Computer PC, Intel Core i3-4130 3.4Ghz, 8GB RAM, 500GB SATA HDD, DVD Windows 10, includes 19" LCD, keyboard, and mouse, 1 year warranty - Walmart.com