Craigslist has some decent towers sometimes, as long as people aren't autistic with their descriptions. Find something with an SSD, 16GB+ of DDR3 RAM (DDR4 would be nice, but is expensive), 450-650+ power supply unit (PSU), and a competent video card. The case doesn't need lights and stickers. Also factor in peripherals like a mouse, keyboard, speakers, and monitor etc. if you don't have any of that.