Just for your information, when technobit send their first batch of HEX16A, my board stuck on speedy office for more than 3 week because marto issue full prices invoice. Speedy demand marto to issue low prices invoices(Proforma Invoices).
The 10 USD per board is my suggestion

My second order HEX16C use UPS as carrier & i didn't find any invoices but marto declares the miner as SAMPLES

And again no import tax

Since the miner come with no case, then there is no problem declaring it as SAMPLES(which should be free)

Low prices = No import TAX = Quick custom clear
As I said German customs can be really tough. Recently I had a case where I had to get to the tax office and prove to them that usb miners were worth what was on the import tax statement. I could not prove it because it was rediculous low. So I had to pay important taxes plus 100+ euro fine for cheating on import tax.