The parts depend on what the system will be used for. Basic online browsing can be done on a simple, low cost system.
Games require a much higher level of performance so the components must be correspondingly suitable and thus cost more - goes out of budget very quickly.
What game(s) do you wish to play? How else will the computer be used: work, school, streaming....?
Most games and software applications provide a listing of the necessary hardware components. Usually categorized in some manner such as minimum, recommended, or best.
Look at the games you wish to play. Find the hardware specs. Make a list and then use an online resource such as pcpartpicker:
https://pcpartpicker.com/guide/DGzKHx/great-intel-gaming-build
Use the build guide. Select components from one of the recommended builds in the Tom's link above.
Put together a few builds. Just to learn the process and get a sense of the costs involved.
Decide what you want and then post your "build" accordingly. Ask for comments and suggestions.