Decent Sandy/Ivy Bridge LGA2011 motherboards are becoming harder to find these days (E5-1620 v2 is an Ivy Bridge CPU), and they are not cheap. I am actually not sure that the linked ASRock X99 Extreme3 would be compatible with your CPU. It has a LGA2011-v3, i.e. Haswell socket, X99 chipset and DDR4 memory slots. What you need is X79 based board with DDR3. Even though LGA2011 socket is physically the same for Haswell, it uses different signalling, so Ivy Bridge CPU would probably not work in that board.
I ended up buying a used Lenovo S30 workstation on ebay for ~$100, just to get the motherboard (and I received a small bonus in extra parts). Or there may be other brand workstations available out there, if you don't mind buying used. If you want to go this route, make sure the board will be Ivy Bridge (v2) compatible, and not only Sandy Bridge. If interested, LMK and I can help you with the exact Lenovo S30 model numbers to look for
I was also looking at some Chinese LGA2011 / X79 motherboards you can buy on ebay or aliexpress (brands like RUNING or HUANAN). You can search to get peoples feedback about them. Some of them seem to be decent boards, but I don't have a personal experience with them