It seems it's a difficult paper to obtain in some places even though it's made in Italy. Anyway here is a nice link
http://www.paperideas.it . It is the Fedrigoni site for their paper. It's customer friendly and you can request samples. It comes in multiple languages (it, ger, eng, fr, spanish) and is a good over view of what this particular paper company offers.
I have always had good experiences when dealing with them and we all love he paper. So if you are having issues obtaining Pergamenata through conventional means I suggest trying out this site, seeing if you can get some samples or contact the local contact given ( on the side bar) You will probably have to create an account with them but they don't spam you and the benefits are great.
Bridget- who still has some pergamenata for sale.