My wife and I brought back quite a few coins from Mexico during our last visit there. I am currently searching for the storage box which contains them. I have promised Triggersmob I would send him some. If I have duplicates, I would be happy to send them to you also.
Our oldest son and his family plan a vacation to Puerto Vallarta in March. I will be sure to have him bring back coins. I would share them with you and Triggersmob.
Regarding friends or coin collecting associates in Mexico -- sorry, I don't have any.