If it were me this is what I would do:
Monitor - LG 22M34D-B
Keyboard - Logitech MK120
Case - Corsair Air 540
I personally have this case and love it, good choice.
Motherboard - ASUS X99-E WS
Can be upgraded to 4 GPU later down the road if you guys ever need to.
CPU - Intel Xeon E5-1650 v3
You will thank me for this CPU choice over the 1603. Clock speed on the 1603 2.8, the 1650 is 3.5. Spending more money here and only going with 1 GPU will save you a lot more render time than having two GTX 970 video cards
RAM - Crucial 16GB DDR4-2133 ECC
CT16G4RFD4213
See RAM comment below
CPU Cooler - Cooler Master Hyper 212 EVO
This CPU cooler is amazing for the price. I use it as my default for all builds.
Spinning HDD - HGST Deskstar 3TB
H3IKNAS30003272SN
I just prefer HGST and have never had a problem with these at all.
GPU - EVGA GTX 970
04G-P4-3975-KR
PSU - EVGA 1200W P2
220-P2-1200-X1
10yr warranty and platinum rating, enough said. Will support 3-4 GPU depending on their power requirements.
My recommendations above put you right at $2988.39 and give you a LOT of room to upgrade down the road.
The above comment about DDR4 is correct, it is a little more expensive right now, but the prices on DDR4 are dropping almost weekly since it is becoming the mainstream RAM. Pay a little extra now, but when you want to go from 64-128GB later it will be much cheaper than DDR3.