Collecting from deadbeat customers

Well, small claims court isn't an option as the amount is higher than the limit. I've been talking with them for a while and they keep promising to make good on their debt but haven't done it so far. Now the last 2 weeks or so I don't get any response from them at all.

I spoke with my attorney, he said that we'd have to sue them in Supreme Court, and it'd cost me quite a bit to do that. I've seen some places that say they'll handle collections, and I there's no fee unless they collect. But then their fee is like 30%. I wouldn't mind paying that if they could collect the whole amount owed... Anybody have any experience with that?