Answer:
Of these things - I have two. One for me - and one for you. And when you ask about the price, I simply smile and nod twice.
Goes over all the hills and hollows. Bites hard, but never swallows.
The person who makes it has no need for it. The person who purchases it does not use it. The person who does use it does not know he or she is. What is it?
What measures out time. Until in time all is smashed to it?
I know a word of letters three. Add two, and fewer there will be!
Some women don't like to be called that, yet every woman wants one. It cries and makes a lot of noise, but smiles and gurgles when you give it toys.