To give you an idea, a fairly 'top tier' gaming PC here in Australia, built from scratch would be something like:
NVIDIA RTX 2080ti Graphics Card: ~$2100.00
Intel i7 8700k CPU: ~$500.00
Decent Motherboard: ~$250.00
16GB of decent RAM: ~$300.00
750W PSU: ~$200.00
500GB SSD: ~$200.00
Decent Case: ~$200.00
Basic CPU Cooler (liquid or fan): ~$100.00
= ~$3850.00
And those are just estimates. You want a decent size HDD as backup? Add some more. Want a more efficient PSU? Add some more. Want a super powerful 3-fan liquid CPU cooler? Add some more. Want liquid cooling on your graphics card? Add some more.
You can probably built a basic PC for between $500 and $1000 if you really scrounge around, but it's not running anything made after 2010 on Ultra, probably not even on high. A 'high end' PC is pushing into multiple thousands of dollars very easily.