fuses - the $39 ones or the 85 cent ones

Very true about ISO.....and good catch!
ISO basically says that you 'say what you do' and 'do what you say'....In other words, you follow your own internal specifications and documents.
They could care less if it actually works!

I don't know how costly it is to have UL listed or any other certification, but during my search all 2.5A and 4A fuses have UL and SA certification, except of course for HiFi-Tuning fuses. For instance, the Isoclean fuses have UL SA PSE and CE certifications, the Littel Fuse fuses have UL, SA and CE certifications, and Buss fuses have UL and SA.

It seems to me that they pursue the certification in the market in which they will be distributed. I don't know the certification story of HiFi-Tuning, but if they have it, it is odd that they don't post it like everybody else.

Couple 'o thoughts.
I would suspect you are right: get the certs of the market you intend.
Small companies, even those making, say, 10,000%, probably can not afford such certs.
If, BIG IF, HiFi-Tuning is small, like 3 or 4 employees who would usually all be relatives and owned by 1 guy, than I would expect no certs, now or in the near future. This, in and of itself is meaningless. When's the last time somebody Sued UL for a product fault?

I don't know how to do the numbers here, but if HiFi-Tuning could make more fuses and drop the price, his profit could actually increase. Of course, the market for 20$ fuses is probably not double that for 39$ fuses, so he may lose and end up with a garage full of un-sellable fuses.

Many other approaches, too. Like getting a couple OEM contracts......make fuses for BigTime players. Of course they'd hammer him to death for a low price, but his name would be out there in wider distribution.

Happy Listening.....

You're right about it. Everything that's not mass-produced, from fuses to cars, will carry a higher ticket price. If they do everything in Germany, plus the current value of the Dollar against the Euro, then they may easily end up with a $39 fuse in the US.

The funny thing in audio is that sometimes high price does not translate into high performance, or conversely, low price does not mean low performance.

I'm disappointed and happy with my test. I'm Disappointed that the fuse specifically called "true audiophile grade" didn't do better than its cheaper ceramic cousin made in Taiwan. I'm happy that what works for my particular case costs just $1 & 20cents. And that is a true audiophile deal.

Why surprised that price/performance are not related?
A current 25000$ Honda Accord handily outdoes the same price car from the dawn of Acura...the 25000$ Legend.
More features, safer, as quick or quicker, better economy.
The works. And that is before I count 22 years of inflation!
That's a deal!
I have a 10 Euro note on my shelf.....I can dream, can't I?
It cost about 8$ and is now worth about 15$.
I wish I had invested BigTime.