A few major desktop manufacturers allow you to customize desktops to suit your personal or business computing requirements. In order to customize desktops you will need to purchase the computer direct from a manufacturer's online store rather than buying through an indirect desktop merchant. I always recommend starting with the base version of a desktop computer and customizing as needed to meet your personal or business needs. Perhaps a base desktop version is all you need in which case you get the cheapest price.
To customize desktops you'll have to consider features such as processor type, processor speed, system memory, hard drive storage capacity, operating system, optical drive options, wireless card options, video card options, sound card options, and monitor screen size. Additional features that can be added include TV tuners, productivity software, printers, wireless network supplies, power adapter options, and various desktop accessories.