to be honest building a PC these days is much more expensive than it used to be due to cryptocurrency mining.
I recommend getting something from Dell, MSI, Acer, ASUS, etc. and if you're looking for a laptop there should be some really good deals. it's too bad you missed the memorial day sale that dell had. the prices on Alienware systems were astronomically cheaper than building a PC yourself.
for this laptop pricerange, make sure you're getting a display that is 1920x1080 at 120hz and hopefully G Sync.
I advise you to be patient and wait for a deal on something you like and has great performance for the money.
check out these as examples:
that website is really good to check every day or two to find deals on gaming laptops and anything else related to computers/video games and other stuff. it's basically just a forum where they post deals. but try to avoid the "sponsored" posts as it's mostlikely not as good of a deal.
if you end up building or buying a desktop, I would shoot for a PC under 800 bucks and then getting a 1ms 144hz monitor and a rapid response keyboard and mouse.