Without a doubt, the best place to go for this is www.chiffandfipple.com/. Check out the discussion board and sign up for the newsletter - you'll be rewarded with contacts & information. This topic has been discussed there- and, I think there may even be some discussion of flutes as well as whistles. It's a human and personable site/community - I know you'll find and get responses. Webmaster Dale has created a great and indispensable e-community ... they should be part of Tribe, but I know it pre-dates.

Also, I have a friend who's quite particular about instruments he eventually buys: he's contacted various makers in Ireland & elsewhere directly, and most of them are sole proprieter craftsmen. Although more brazen or courageous than I, he's certainly made contact with some interesting people and has found out much information.

Good luck!