When two parties agree to exchange goods and one fails or refuses to comply with the terms of that agreement, the one who fails to comply can be sued for breach of contract, penalties may range from compliance to damages, fines and fees, or all of the above.
Defendants generally have to be sued in their home state and county, however, which can make filing inconvenient, but the court can award costs associated with the expense as reimbursement. These kinds of suits can of course be filed with the assistance of an attorney, but they can also be filed without an attorney in many cases by contacting the court where the suit would be filed for appropriate forms, and depending upon the monetary value of the items the claim may be filed in small claims court.
In addition, the perpetrator of such online fraud can be reported to the local police and the FBI, which you can find more information about HERE. This is important, because there are both state and federal laws which he may have violated.
And lastly, if the agreement occurred on a particular forum, such as amazon or ebay, the fraudsters should be reported directly to them. This is because they can conduct their own investigation, which may provide information that could support both the civil suit and law enforcement (see above), and they can levy other punishments, such as fines and bans.
I hope this information helps, feel free to follow up with any additional questions you may have. And please remember to enter your rating so that we can improve the service we provide. Thank you.