I wouldn't use a collection agency if you have to pay a fee up front. You collect from them, you collect from me! IMHO they would work harder and put in more effort if there fee is dependent on the amt they collect.
My bookkeeper recommends small claims court for debts. Cost is small but success is high. I only have a couple of bad accounts but that is what we are going to try. From my understanding if they continually blow you off it becomes a criminal offense and they could actually go to jail.
Sounds good to me