Check out my tour calender on the news page. I always have whistles with me when I'm on tour so you may be able to get one directly from me if I'm playing close to your town.
If you don't want to pay straight away via paypal to order a whistle. Email me and I can put your name on a list. I can contact you when I have an instrument ready for you and you can pay then.
Music stores, Comhaltas branches, online stores, etc. contact me for wholesale prices. You only have to order 5 or more!