Frankly you get what you pay for. If you find some lawyer who will do this for next to nothing chances are he will spend next to no time on it. Either hire a quality private attorney or if your son is impoverished ask for the public defender. Contrary to the impression many people have public defenders are experienced trial lawyers your son can safely trust. Because of their case load they often do not give the personal attention some accuseds want but who cares if they negotiate a good solution or win your trial for you.
In many cases, hiring the best defense is what you would like to do but may not be what you are able to do. Finances often dictate if and what attorney clients can afford. I agree with my colleague in that if you or your son cannot afford an attorney, a public defender will be appointed to your son's case. And contrary to popular belief, many public defenders are tremendous trial attorneys. They are experienced lawyers and often are familiar faces with that particular court, judge, and staff. And those things go a long way.
However, if you are looking for an attorney that might be affordable, it takes quite a bit of footwork. One way to go might be to contact your local bar association. There are county and local area bar associations that have referral services. For example, if you are in a certain area or valley, you might look to see if there is a bar association covering your area and contact them. They might refer you to a private attorney that you might be able to meet and get an idea of your son's legal options, the severity of the charges against him, and ultimately how much it would cost to hire a private attorney. Even if you have to pay for a consultation fee, the one time fee might very well be worth the money to get a 2nd opinion. If a doctor told you he needed to do surgery, you might get a second opinion before going through it. A second opinion might confirm your feelings about the public defender being a good lawyer and/or how much it might cost your family if you hired privately.
DISCLAIMER: This does not constitute legal advice but is information based upon generalizations.
Well, if you can not afford a lawyer your son will be assigned a free lawyer from either the public defender or legal defender. There are plenty of attorneys willing to charge flat fees but for someone on SSI I would imagine the fee would be pretty significant.