No, they aren't cheap but you don't use much, usually just a fraction of a bean, and they last forever in a sealed jar.
They're hard. I grate the bean with a microplane until I get the amount I want, then put the rest of the bean back in the jar.
You can also put the whole bean into sugar, or maybe ground coffee, like a vanilla pod, to infuse it with tonka flavour. Which, btw, is intense. It would be difficult to diminish the intense flavour of Tonka.
I like tonka with chocolate or custard, ice cream would also be good. I just grate some tonka in the milk for custard, or with the chocolate.
Baking doesn't seem to affect the taste. I put the tonka in with the boiling syrup when I made the jam, and it didn't affect the flavour.
I used about a teaspoon of shaved tonka to 4 kilos of apricots. That was about 1/4 of the bean.
I've never tried tonka with savoury dishes, I suppose it might work, I can't really imagine it.
If anyone tries it, I'd love to hear about their opinion!