A common misunderstanding is that free software (replace the terms with "open source software" as you wish) will never involve costs. While this might be indeed true regarding you don't need to pay for licenses, they often don't understand
- you might have to pay for actually getting access
- the learning curve might be steeper (which means more costs)
- you might have to pay for support, and are surprised if "customer" service will not help out for free
- you might want to pay somebody to extend the software
- developers generally need something to eat and live from.
I'd love to make them understand them the freedoms involved, how to benefit from those, that they are (or should be) part of a community and if possible return something to the community (for example, pay somebody to develop new features and put them back into the original product).
How to make customer understand free software might involve costs, but brings advantage beyond licensing costs?