IMO if you "just want box that make play video game go whee," you should just buy a console (the Steam Machine, for example). That's literally their purpose.

Anyway, if you, for instance, just buy parts using recommended parts lists (some of the review sites have good enough builds, or you can just use the brain dead "build with AI" option on Newegg), you could probably just pay a computer store to build it for you for a lot cheaper than $1k.

Or you could just read the manuals and build it yourself since the manuals are usually pretty straightforward with pictures showing you what to do. It's basically just an expensive LEGO set lol. Really, as long as you can read a manual with pictures and use a screwdriver you're pretty much good.