Building a PC takes almost half of a Sunday afternoon, and it's easy and fun.
If you don't believe it's easy, watch this 5 year old build one and then tell me you'll have trouble. Now that you've told me, have this guide that you can watch while you're building to make sure you're doing it right.
Cool, there's the how. Now for the what. Below is a Fantastic build that will not cost you anywhere near $1800 but will wreck the performance of any laptop in that price range. Justification for the parts is immediately below.
It includes a copy of windows from /r/microsoftsoftwareswap, and you'll have plenty of $$ leftover for keyboard/mouse/headphones (have a guide to gaming audio)/MONITORS! And maybe a TV.
PCPartPicker part list / Price breakdown by merchant