jeez madman. some good advice man.
SEF... computer hardware market is cut throat. you looking at 30% max markup. ALthough your overheads are gonna be near zero. depending on supplier. if you can get it from Rectron or equivalent distributer, then you compete with all the retailers, who take bigger margins since they pay rent on floorspace. In the online world, there are more shopping sites in south africa than good cheeses. no not jesus. cheeses. and 90% of them order on demand, so they hold no stock. pretty cheesy.
Basically... getting into hardware requires purchases directly from manufacturers at a container level. if you can streamline this supply chain, find the required capital, and actually handle the risk of buying a container full of CPU's you know will sell, then, you could be a rich man.
in some instances you can throw in a bit of social engineering, convince some university they need a supercomputer, and thus create your own demand.