I’m taking orders now for my new tunable wooden whistles. I’m very happy with them- they have a sweet clear sound, medium volume. The tuning slide is brass-on-brass with the same bore as the rest of the whistle. The mouthpiece is Delrin or brass and the fipple is Delrin. I think the price is very reasonable: C$150 (US$130), which includes a two pocket tweed wool drawstring bag and shipping.
You can see some photos and hear a sound sample here:http://www.obrienwhistles.com/maple.html