Staffan,
Peter writes:
"..[clients] must participate out of their own free will because they realize that this is beneficial to them."
One way, is to present two bids/estimates per project. 1. with propreitary solution/development/maintenance 2. with open-source solution/development/maintenance. Giving the client these choices shows that you are willing to support them regardless of their decision. If they choose propreitary way, the resources needed to support that usually benefit the company enough that it can turn around and support "sacred-cow" open source projects of their liking.
