therogerwilco :
400$ is way too expensive
Please remember that this is a HEDT MB so it can't come cheap.
AsRock has the nicest mITX portfolio which not only covers almost all the new chipsets but also ticks all the feature boxes !
All the other mITX MB lack one (or even more) of these features: TB 3.0 (on Intel platforms ofc), Bluetooth, WiFi, ALC 1220 sound (for the Z270 chipset for example AsRock's mITX Gaming/ac was the only one, all the other MBs were using the 'older' 1150 or even older than that), HDMI 2.0 (where applicable) etc.
I personally bought the Z270 one after Thomas' review and although it was the most expensive mITX it also was a no brainer buy !
You (and others) said it's expensive because you have only thought price without thinking value. These mITX boards do excellent living room passively cooled machines far cheaper and more flexible than any of the shelf network streamer I know. Think about using an ATX or even a micro ATX behemoth instead (and yet you won't find many passively cooled cases for that sizes).