I am a Maximum PC magazine subscribers, one of the best computer magazines and one of the few magazines still surviving as a print magazine (you can still read it online).
Every year Maximum PC have their “Dream Machine” of the year which is a custom computer that they build using the best of the best hardware, and they are expensive ($17,000 last year). So this time they presented 3 different Dream Machines at the following price ranges (2,600SR, 5,400SR and 14,000SR). The specs on these machines are pretty good, even the cheapest model. Although we know how hard it is to find AMD products in the Intel-dominated Saudi market.
As for where to buy the hardware in Saudi Arabia? Most of the standard hardware can be found at regular computer stores but if you want the high end video cards, power supplies and cases then you need to visit a store such as Softland/Binaries/Techno Roof. The other solution is to import from the United States using any of the mail forwarding services listed here.