i paid about $300 for my desktop
decent case, motherboard, cpu, and power supply for about $120 from a friend
ram was 8gb and cost me about $80 i think
cpu was amd phenom 2 x4 970 @ 3.5 GHz
gpu was nvidia gtx 650ti which is good enough for any game that was made before 2013 that did not need super graphics to play on, so basically it could play the same graphics as an xbox 360 or ps3 game and it cost me a little over $100 i think, not you might be able to get one for $80 or less
i've put in several old hdds that i've had from laptops in there, i would suggest a 320 hdd for the OS and games and get a 2tb hdd, external or internal it doesnt matter as long as the external is usb 3.0, for recording games

so getting a $500 desktop computer will let you do pc longplays as long as the games are either telltale games or games that are a couple of years old or not very demanding indie games

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