You guys can feel free to laugh at this, but you can make your own outta an old plastic coke bottle with the cap on and a piece of bamboo or very wide straw at least half the length of the bottle. Cut a hole in the bottle side just down from where the bottle rounds into the thin part at the top of the bottle, between the size of a penny and a nickel. Start small and play with size and oval shape to get the right pitch. Attach the straw to blow over the hole with some support underneath (I used duct tape, but you could come up with a more elegant solution) so that the straw points toward the hole at an angle. The key is figuring the right angle to get the air flow to provide a nice rich tone. Kinda ugly, but the sound is good and will work in a pinch. I've used it a few times with success.
I personally use a generic knight and hale and the have had decent luck with it.