Acer Japan started to accept the pre-orders on the Rakuten for the Acer Windows Mixed Reality Headset Developer Kit. According to the press release and the Rakuten product page, the kit with the headset will be available from August 31, 2017 and the price is 40 000 Yen (with tax) (about 360 USD / 320 EUR / 277 GBP).
This headset will be compatible with the Microsoft’s own VR system and if you compare the prices with the Microsoft HoloLens which costs 360 000 Yen, this Acer one is the cheapest option. Of course you can’t expect the functions or the preformance like with the HoloLens but if you are interested in the Microsoft VR world from software side this is a great option to start the job.
You can pre-order it from here: http://item.rakuten.co.jp/acer-direct/5jr03ww001/