This is not legal advice.
Consider two cheap options: not paying wages, including overtime, most likely violates the Fair Labor Standards Act and a similar state law. Consider getting in touch with your state's department of labor and/or the US DOL: http://www.dol.gov/cgi-bin/compliance_contactus.asp They may be able to help you.
Second option is small claims court, which doesn't force you to pay for the lawyer (with such a small amount at stake, you would want to be fighting this over principle if you got a lawyer involved). You don't *need a lawyer* for any claim, but you will most likely fail in other court by yourself. I also assume that your wife isn't eligible for legal aid?
If it were me, I would try getting the money back through the labor enforcement first.