$180 · Mac Mini, 2.26Ghz, MacOS 10.11 El Capitan

Older mini but still lots of life left....I have been using the identical model for the last year as my main household computer. Plays Youtube and streaming video just fine. Clean install of 10.11 OS. Upgraded to 8GB ram + 240GB SSD drive. 5 USB ports, DVD burner, wifi, ethernet, Firewire 800, 2 outputs for dual monitors, tiny case, almost silent, and uses about 3 cents of electricity per day. I don't have a spare apple keyboard to include with it, but you can use any USB windows or bluetooth keyboard.