A few things:

1) was he paying you in cash directly, or was he paying you by a check. By check you have a much better chance to get him to pay you because there is a paper trail. Unfortunately, most under the table stuff is usually paid in cash.

2) Your best bet is to go into the store, ask to speak with him and ask for what you are owed. Assuming he will be the same jerk he appears to be, you can gently "coerce" him into paying by hinting that an anonymous tip to the State Franchise Tax Board and the IRS about illegal employees and non payment of payroll taxes might harm his business. It would be a shame if an investigation were to start ...

3) Another tactic if you do not want to confront him like that is to report him to the INS or the state franchise tax board saying there are tons of undocumented workers there, and they should investigate. Whether they are legal or not, odds are they will look into it just a bit.

Trying to sue in court would be hard, since he will just deny that you were ever an employee. If you have anything that is company property, your odds are much higher that you could win (uniform, employee card, company literature, even pictures of yourself working there or at a company party).

Pay him a visit, maybe smash a few windows on his car or something. Show him you mean business.

Contact your state labor board and tell them what is happening. You'll get help from them. Not paying wages and paying people under teh table is a big no-no in their eyes.

You can sue in small claims and you can call the labor board, HOWEVER you are opening yourself up to some legal problems since you were paid & accepted money under the table. The tax people can also come after you and you would owe taxes & probable penalties. You will need to decide if this is worth it.