Pixie, I was stupid with my ex, too, so I feel your pain...
If you go through OCSE (Office of Child Support Enforcement) you DO NOT have to go through the expense of hiring an attorney. However, their caseload is INCREDIBLE, so it'll generally take more time to get something accomplished. But at least you won't be losing whatever you get by paying it out in attorney's fees!
Most of the time, the court will take NO action UNLESS the payment is at least 90 days in arrears. When it DOES go to court, chances are they'll let him make monthly payments to pay off his arrears – and it's usually only about $25 (or less) per month in addition to the court-ordered child support. That means it'll take you nearly two years just to recoup $500 in back-support! So don't let it go too long...
Also when you get to court, be sure to ask for the wage withholding option so they can take it directly out of his paycheck. They can also intercept any tax refund and apply it towards back child support. The driver's license thing is usually a "last ditch" effort, used to bring in the ones who fail to respond to subpoenas to appear in court. If he's self-employed (like mine is) your options are somewhat limited because you can't garnish wages and they usually OWE taxes...
Good luck! PM me if you need more info!