400 MHz Sonnet upgrade for $29.95 here:

https://secure1.sonnettech.com/index.php?cPath=22_91&osCsid=a3bf1e35523d314892d644e078aa4401

The PDS pass-through is also available there for an additional $19.95.

Back when, Sonnet was not compatible with the NuBus JackHammer card and the NewerTech upgrade was. I don't know if they solved that problem. I think they eventually did, but I can't swear to it.

Oh, looks like you're in Finland. I don't know if they do international shipping, or if they're reasonable about it, if they do.