Wanted - Austrian 25 euro silver-niobium coins

Hi,

A friend of mine wants to buy a set of Austrian 25 euro coins, started in 2003, silver-niobium coins like that:
https://en.numista.com/catalogue/pieces27912.html

In Austrian Mint shop they are "sold out":
https://www.muenzeoesterreich.at/eng/Filter/View/?bereich=Sammeln&produkt=true&kategorie=_kategorie_Silber-Niob_kategorie_Bimetall_muenzen

I'm checking now ebay to find a seller with all coins...

And also I would like to ask here:
Would you recommend somebody who can give good price for these coins?
Or online coin shop?
Any suggestions are highly appreciated!
Thanks!