This is what our service unit began doing a few years ago and it works fairly well.
We give out "funny money" for various activities. Helping plan service unit events, being on a committee, attending Service Unit activities all earn leaders "funny money" during the year. You earn money based on how hard the work involved is. For instance, attending an event or Service Unit meeting earns you $100, but being in charge might get you $300, a Service Unit cookie manager might get $400.
At the end of the year as part of our leader appreciation dinner, we have an auction. A committee gets donations from various businesses in our town (they have all been very generous when we tell them its to thank GS leaders) and some things are bought from the council shop (T-shirts, books, etc.) with Service Unit funds for recognition.
Most everyone in the Service Unit seems to enjoy this idea. Lots of them try to see who can earn the most money by the end of the year.
One of the leaders designed our funny money, it varies in color from year to year, but usually has a trefoil in the center.