Anyone who wants to play with tinkering a whistle, run out and but a "Generation". They almost always need severe tweaking in order to sound and play halfway decently, but are cheap enough so it's not a big deal if you bollox one up in the attempt. Give the failures to your little Nephew or the bratty snotnosed kid down the street to annoy his parents with!
I'd stick with the little weeine ones (the cheapest, generally) until you get the hang of it, though.
Properly tweaked, a Gennie can be a pretty decent whistle, actually.
They make a great backpack / auto console sort of instrument that can take a beating and are not a big deal if some gremlin walks off with it or it gets run over, slammed in the door, or otherwise falls on bad times. You don't want that happening to your Oak, Cheiftan, Susato or Soodlum, now do you?