What is it?
Money is a nice and clear concept to work with: people understand what it is and can make assessments based on money. But it is a misconception that people are only motivated by money and their own interest. Other factors are also important when making a purchasing decision, for example what other people (or companies) do.
Discuss the financial side, but also other topics, such as the
environment, doing something for others and society or how cool technology is.
Emphasize payback times instead of investment costs.
Volkskrant Column Ad Badenhorst on the myth of self-interest and happiness
Volkskrant column Mark van Vugt on the Myth of self-interest in evolutionary perspective
Dale Miller (1999). The norm of self-interest. American Psychologist, 54(12), 1053. Link
Michel Handgraaf, Margriet van Lidth de Jeude, Kirstin Appelt (2013). Public praise vs. private pay: Effects of rewards on energy conservation in the workplace. Ecological Economics, 86, 86-92. Link
Jessica Nolan, Wesley Schultz, Robert Cialdini, Noah Goldstein, Vladas Griskevicius (2008). Normative social influence is underdetected. Personality and social psychology bulletin, 34(7), 913-923. Link