90€ for a thinkcentre with a quad core i5-6400, 290€ for the best gpu you can get (used, check power consumption), steal a mouse & keyboard at work for free, 20€ for a good soup and you're good to go.
I bought mine in a pricey country for around $350 and upgraded the RAM for a $100. Since I play mostly discounted games that are at least 5 years old it's been great. Highly recommend giving the devs some time to finish the game after it's released (looking at you Cyberpunk)