In the case I mentioned above it was, of course, a lot more than just a will as the documents had to be prepared for each of the children and a meeting arranged so that the Notary was satisfied that they understood what they were signing.

The will itself was about CHF 800.- and the Pacte successoral was about CHF 850.-

I can't answer your question about an official notary but I think that any notary could do it.