There are dozens of reverse phone look-ups online. Of course, you have to pay to get all the information that you want...but there are hundreds of creeps willing to do it.
But they could do the same to your mom. Not to mention, her phone could be overcome with nutobs just messing with her.
Why would you use a phone number at all? Use an email address instead and then if a buyer contacts you with a serious offer, switch to calls to solidify the deal and set the pick-up time.