Kasper Jorgensen :
You should be able to get a case and OS for $200. But as Hellfire suggested you could get the stronger GTX 1080 TI and lower the CPU to the I5-8600 Instead. Just consider the better samsung SSD than the WD. Also $250 for a mobo, you shoudl be able to find a lot cheaper.
For gaming don't get the Ryzen 7, the new Coffee Lake will blow it away even more than the I7-7700K are already doing.
SSD speeds are already pretty fast, and a faster SSD does not contribute anything extra to gaming. Faster SSD speed are beneficial for non gaming workload only.
The board comes with lots of connectivity options, overclocking potential due to better VRMs and features like superior audio codec with headphone amps, bluetooth and wifi and one of the better bang for buck units.
Agree with the Ryzen though.