I have Tera and love it - my favorite purchase ever and for sure the best sound I have ever heard with my 1plus2 or Koss Porta Pro phones (as good as vinyl and I never though possible in my lifetime to have digital reach that and especially in such tiny portable device). I love the ergonomics almost as much as SQ (it's a dream operating by touch with device in pocket and not needing to take it out and deal with touchscreen or tiny buttons on the sides of some touchscreen devices - hated that on my iphone).
Here is a recent video showing the assembly of one Tera. I think after watching this video it should be easier for (open minded) people to understand the cost (it is completely hand made). Research cost is only "recovered" in the step when the device is briefly connected to computer to transfer the firmware - so what you are essentially paying for with Tera is the time and skilled hands of Charles Altmann (I have no problem that someone with that type of very unique skill-set demands several thousand euro for several hours of his time required to assemble this - it is not uncommon for top engineers to demand those types of salaries).
For the record, I joined this forum specifically to learn about at that time upcoming hm-901 as that was what I planned to purchase (based on published specs and few reviews). After waiting for it to be released (there were delays) I ended up with Tera instead (after reading all the closed Tera threads I became intrigued). I have no regrets whatsoever even though I have never heard 901 (I have heard AK120 and Tera clearly wins that SQ head to head match-up in my opinion).