Answer:
I am the tool, for inspiring many. Buy me in the store, for not much more than a penny. Don't overuse me, or my usefulness will go.
It stands upright and can be quite grand. Its secret is not hidden but right at hand. What is it?
It's usually found dried, but often kept slicker. Above another need, it's said to be thicker. What is it?
I'm white, I'm round, but not always around. Sometimes you see me, sometimes you don't.
Up on high I wave away but not a word can I say.
When is it bad luck to see a black cat?