So - we recently published an article about the qualitative side of this, but in the introduction you can find some of the quantitative methods for evaluating Cultural Ecosystem Services too.
Article The 'desert experience': Evaluating the cultural ecosystem s...
Seed dispersal as an ecosystem service: seeds --> dispersed --> seedlings --> trees --> attract birds --> creates sanctuaries plus control predators in conjunction with indigenous people --> attract visitors --> pay to view --> $ & GBP