One strategy that I've used, during 'economy times' in the past, has been to specify a system configuration completely, down to the part numbers and suppliers, and pick-up one item every two weeks to a month--depending on the cost of that item.
Before you know it, you have a full-blown system.
Doing it that way gives you the advantage of the sales and discount pricing that often comes-up, over time; and, starting with a case ans PSU gives you the ability to do a bit of a change-up on things like processors, memory and GPU, as the build evolves.