because i’m searching for a proper Higonokami knife, and have no ideal where to start and what to look for.
I do want something with proper quality, so no cheap 30€ knife, and i found 130-200€ Higos, but i don’t know if they are worth it.
e.g. http://www.couteaux-berthier.com/higonokami-knife-myamoto-musashi-damas-bs-ref-016794,us,4,016794.cfm
Are there any good known japanese manufacturers? And maybe an online shop? 
hmm i dunno both this might help
Samurai Buyer
they help buy and export stuff from japan to your place, so some kind of paid representative in japan for you.
but, you still need to find the source in japan yourself.
or you can just take a look at their catalogue / list of higonokami