@kaidubin Under $800 U.S. for a desktop does work, although only barely. It's a good price segment normally, but most gaming desktops in that range are sold out right now, probably due to all the people stuck at home with nothing to do except play games. I did find a couple of good options for $750 though.
The first one has a strong processor and a graphics card that should run all current and future Sims 4 content together on ultra settings. The second has a faster graphics card and a weaker processor, although it's still far stronger than Sims 4 will ever need. They both have a 240 GB solid state drive; the first one has a 2 TB mechanical drive, while the second's HDD is 1 TB. That's still plenty of storage though.
https://www.bestbuy.com/site/cyberpowerpc-gaming-desktop-amd-ryzen-5-3600-8gb-memory-amd-radeon-rx-580-2tb-hdd-240gb-ssd-black/6362427.p?skuId=6362427
https://www.amazon.com/CYBERPOWERPC-Xtreme-i5-9400F-GeForce-GXiVR8060A8/dp/B07VGJDKZ4/
They both only have 8 GB memory, which is plenty for Sims 4 but might not be enough for multitasking if you like to run multiple other apps while you play. (Not that it wouldn't work at all, it's just that switching would be somewhat slower.) But you can add RAM after the fact easily enough, and it might only cost you $40 to get a matching 8 GB stick.
As for monitors, there are too many good options to list without knowing the size you want, or any other considerations. These are a good place to start though:
https://www.amazon.com/Acer-SB220Q-Ultra-Thin-Frame-Monitor/dp/B07CVL2D2S/
https://www.amazon.com/Samsung-Business-S22R350FHN-1920x1080-Monitor/dp/B083W8PJPB/
https://www.amazon.com/AOC-24B2XH-Monitor-Frameless-Compatible/dp/B07WVN1N8C/
https://www.newegg.com/asus-90lm0351-b014b0-21-5-full-hd/p/N82E16824236986?Item=N82E16824236986
https://www.newegg.com/lg-22bk430h-b-21-5-full-hd/p/N82E16824025903?Item=N82E16824025903
https://www.newegg.com/asus-va24ehe-23-8-full-hd/p/1FR-000R-00024?Item=1FR-000R-00024
They all have IPS panels, the highest quality screen, and they're all made by good vendors. (AOC makes the panels for other name brand vendors but is not well known on its own.) A few of them have a 75 Hz refresh rate rather than the default 60, which makes a difference to many people but not everyone.
Normally, I'd suggest you go to a Best Buy and physically look at the monitors, so you get a sense of what manufacturers' products you like looking at. All monitors of the same type (i.e. IPS) from the same manufacturer will look pretty much the same once you take size and resolution into account. If that's not possible though, maybe a friend or family member of yours has a monitor you like, and yoy might want a similar product. Or if you know of a type of monitor you don't like, you can cross those off the list.
If you're not sold on any of the above monitors, let me know what details matter to you, as well as any manufacturers that you do or don't like, and I'll take another look.