The best bang for buck on a display is going to be the cheapest 4k monitor you can find online at best buy or at walmart.
ones at walmart are rather pricey if you want something that has enough screen to look at.
walmart sells a prebuilt gaming system buy ibuypower. it sells for 800$ here in michigan. Issue is, it has a 1650 gpu.the gpu is selling online right now for 400-550$ depending on retailer and time of day and time of moon cycle.
Most CPUs have been given a 100-180$ markup no matter what they are. However, AMD is even more desireable even after the price gouging as Intel already cost several hundred more before the scalpers came out to play.