1. Kahneman and Ariely both mention in their writings how their is a difference between free and even just 1 penny. Especially given how popular Freemium is I thought this might be a good topic for you to cover. (Ariely calls this "market norms" vs "social norms")
2. A common theme here on HN (mainly from people like Patio) is to "charge higher". I couldn't find a place that explicitly mentioned this. Many people perceive higher quality and value of products and services simply because they cost more (regardless of whether they actually do or not)
3. No mention of Kahneman?!?
This is awesome regardless...saving it and sharing it with some clients.
Feel free to contact me directly if you want me to elaborate on any of this.