Find/make me a gaming pc? Id be hugely grateful?

So, my birthday is coming up in 2 weeks and I would really like to buy a gaming pc. Could you guys either custom build me one or find me a good one on ebay or other sites as i don't have much knowledge on gaming pc's, in terms of specs and graphic cards etc… I would like to run games like rust, minecraft, dayz on medium settings with good fps, so there's no lag. My budget is arond £450, thanks guys, ill love you forever xD