You are going to have a tough time collecting this amount cost-effectively. Generally speaking, to appear in a U.S. court a a business, you will require the services of an attorney. Very few attorneys will take collection matters this small on a contingent-fee basis. You can prosecute this matter in small claims court in California without an attorney (indeed, you are not allowed to have an attorney in small claims), but you would need to appear in person to do so. The small amount of the debt makes this a very difficult situation.