The cheapest processor came in first. The Athlon X 880K didn't do too badly: the power consumption was at a tolerable level, the speed was okay - only complex calculations, for example with architecture software, require patience. The catch: it does not have a built-in graphics chip - which cost valuable points.
AMD Athlon II X4 880K - 4 GHz - 4 cores - 4 MB cache memory
FM2+, 4 GHz, 4 -CoreFree shipping starting at 30,–