Best way to make members aware of someone ripping people off in trading section?

I sent a member on here money for a part that was advertised in the trading section, and never received the part. I've tried multiple IM's, and even tried sending an email to their private address (based on info from paypal). Because I paid using the "family and friends" feature on paypal, paypal will not get involved, or does not resolve disputes using this method of transferring money (Of course, I didn't know that at the time). Just looking to find out the best, and appropriate way to post to all on this site for maximum exposure to make other members aware, and if there is anything else I can do to nail this stooge.

Thanks