You really cant find cheaper pc's then around that maximum price.
Look here: https://www.ebay.com/sch/i.html?_from=R40&_nkw=pc&_sacat=0&RAM%2520Size=8%2520GB...
(Ebay) and you might find something cheaper. There you have some computers but it's up to you.
At least they exist so you can get a computer that is what you call today as a decent computer...