If you want to play games at 1440p 144hz buy a 2070( futureproof), If you want something cheap that could run 1440p 100hz buy a 2060.
for monitors look on amazon or local stores for hot deals (bought my dell s2417dg 1440p 165hz at 430€ 1 year ago or more and now its at 460-470)
Look for hp omen 25/27 dell s2417dg/s2716dg (those are 1440p 165hz gsync ones , tn but one of best tn you could find, and use to be 400 dont pay more than 480$)
And for keyboards I have a k95 and I recommend corsair (didnt tried cm but logitech romer-g sucks , and for a young enthusiast is not so reliable), Have you thought about buying a k70? .