We started using
Omega Financial to collect out dues. I believe they kept 5% of what they collected, with an additional 2.5% for credit card payments. I think the rates depend on the size of your chapter, though.
I'll tell you this - nothing gets a brother into exec with his checkbook faster than a note from a collection agency. But even though this "power" is nice to have, don't abuse it. Don't send a brother to collections because he hasn't paid his $5 parking fine.
The best thing Omega Fi did for us when I was president was freeing up our Exec meetings. Before signing up with Omega, we spent 90% of our time meeting with delinquent brothers and trying to work out payment plans. Post-Omega, we only had to deal with those details a small fraction of the time, and thus were able to devote more time and energy to other issues.
Get in touch with them and see if it will work out for your chapter. I know it worked very well for ours.