From my perspective, if it were any cheaper it would be free. They've come down A LOT recently. Buy it now on the 2660v2 is ballpark $130, 2680v2 is only a little over $200. Best offers can bring that down a little. The v1's have actually gone up in price lately, so the gap is very narrow.E5 v2 H/s per watt is pretty good and H/s per dollar value is better than E5 v3.
For E5 v2 , we don't need to invest in higher cost DDR4 ram and new system board.
I like E5 v2 CPU. Just hoping price starting dropping soon.
Don't forget that v2's are needed for pcie 3.0 in many cases. Between the power efficiency and the performance improvements, for me it's a no brainer. Some boards only take v1's, for everything else I'll be using v2's from here forwards.