There are different prebuilts brands like CyberpowerPC, iBuypower, Xidax, SkyTech, among others (these are american ones) that are sold through their own online stores, but also through retailers like amazon, and they use off the shelves parts, making them a convenient choice if you plan to upgrade parts in the future. Retailers often have deals on them that are cheaper than going to their website and configuring a machine yourself.
These brands and the configurations available will depend on the stores in your country, but in broad terms, for $750 (considering deals) you are looking for a system that at least has:
- 8GB of RAM
- For storage a 240GB or 256GB SSD, with an additional 1TB HDD.
- For GPU a Radeon RX 580 or GTX 1650 SUPER (plain 1650 is not a good performance for its price). If there are some very good deal you may find an RX 590, GTX 1660, or GTX 1660 ti.
- For CPU an i5 9400F or R5 3600. (A system with the older R5 2600 would be fine, just that there has already been deals on systems with the R5 3600)
There was a thread a few weeks ago in which someone got a system with a R5 3600 with an RX 580 from ~$600 from Best Buy. (
something similar to this one but with a discount)
edit:
here's a decent deal.