. . . I would much rather buy a bare bones system, spec the add-ons, and have it built for me instead of buying one off the rack or putting a system together from scratch . . .
This is my preferred way to build now also. A bare bones includes a mainboard, case, power supply and cables. All you have to do is select components compatible with the mainboard and the description gives enough information to start you in the right direction. Just remember the mainboard is processor specific and has to provide the correct interface for the components you select. Other than that you can choose from a variety of processor speeds, how much memory, video cards if you want to upgrade from what may be supplied on board, hard drive capacity, etc and choose your preferred brand name for all of it. Your new computer can be equipped exactly as you want it (within you budget restrictions of course). Best of all, you can time your orders to catch any sales giving you a lower overall price or maybe a chance at an upgrade you didn't think you could afford.