Nothing wrong with making use of what somebody else doesn't need anymore.
My parents (who are rapidly and easily spending what little inheritane there was, and good luck too them) have always taught my brothers and sisters to pass it on, if she is buying something new for the house then she will ring around and find out which one of wants the old item or if we know someone who could use it and to make sure we have someone lined up to take our old one and on it goes. The Old Man drops his old tools off to the local Men's shed when he replaces them.
Are far as making a few bucks good on you.