The first address you should contact would be the Circolo della Zampogna:
http://www.zampogna.org/It may take a while until you get response. They can direct you towards the instrument makers.
There is a very good zampogna maker in Germany, but due to changes in his day job situation, he is presently not taking orders.
Ilario Garbani has written a tutor book:
http://www.zampogna.ch/negozio.php (scroll down to "Metodo per Zampogna a Chiave").
While the playing technique as such is not nearly as complicated as that of for instance GHB. What makes it difficult is the coordination of the two chanters (and, of course, keeping them in tune).
You should be aware that there are approx. 20 different types of Zampogne in Italy. All the above goes for Zampogna molisana and its close relatives (Zampogna lucana et al., the ones with key ("a chiave") for the lowest tone of the long chanter and the chanters tuned in octaves.
You should reveal where you live - you might have an accomplished Zampognaro close to you and yet never realized he's there.