It would be better you report the user who sent you such pm to the moderator so that he wouldn't for any day reason to send you such pm again or if tempo ban is issued to him after the restrictions he would never think of sending out such pm to any higher profile user here again.
If you do not want someone to send you PM anymore, you can go to Profile -> Personal Message Options to add the user to your Ignorelist. Once the user has been added to your Ignorelist, the person will not be able to send you personal messages on this forum anymore.
About reporting the person to a moderator, I have gave my own opinion, it is highly unnecessary and the person will not be banned because he did nothing against any of the forum rules.
Usually I don't think that is right to send out such messages and there should be an offence to it knowing too well that their intentions to purchase such account wasn't for a better purpose rather for an evil intention as I believe that most of the newbie are eagerly to use some of those reputable account to scam people over here as they believe those people has already gained reputation and people could likely fall to what they posted over here.