That was from something I posted. I can try to answer you, but I want to note that is taken out of context, and it was my belief that the OP wished to try to collect a judgment himself. The remainder of the post was based on that assumption.
If you’re looking for a resource, you could probably start with the telephone book, but the American Collectors Association is the largest association of bonded agencies, and you could do some searching there as well.
http://www.acainternational.org/MemberDirectory
If you want to refer an obligation to a collection agency, many factors will have bearing on the fee: amount of obligation, age, retail or commercial, pre-judgment or post-judgment to name a few. If you’re considering trying to place a single, relatively small obligation, as opposed to a “book of business”, expect a higher fee or even a request for a surcharge for the expense of setting you up in their system.
Weighing all factors, expect something in the range of 25-40%
If you have a judgment to be collected, you and the prior OP would probably be best served by finding a local attorney who does creditors’ rights/collection work. An agency would use an attorney to obtain enforcement “tools” from the court. Skip the middleman in that instance.