Budget a custom PC build.
A build budget works by allocation, not by shopping. Peripherals come out first because a monitor bought from the same pot silently halves the machine, then the graphics card and processor take their conventional shares — around thirty-five and twenty percent for a gaming build, reversed for workstation use. What remains has to cover the motherboard, memory, storage, power supply, cooling and case, and seeing that figure explicitly is what stops a build stalling one part short.
Core allocation
Core budget = total budget - peripherals; GPU budget = core x GPU share; CPU budget = core x CPU share
Remainder
Remaining = core budget - GPU budget - CPU budget
Roughly thirty to forty percent on the graphics card and fifteen to twenty-five on the processor, since games are usually graphics-bound. Video editing, compilation and simulation shift weight toward the processor and memory.
The power supply. A poor unit can damage everything attached to it, and the saving is trivial against the rest of the build.