The only option for now in the app store is to publish for "Pricing: Free"
Because of the nature of Java Script widgets, there is no real way of securing payment after downloading. Because the download automatically provide you with the source.
What about; if Mendix take the full responsibility by promoting to create new apps And updating old widget by providing a Kickback towards the developer based usage of the widget in production?
Yes, it is difficult concept to implement, but it worth considering. Mendix will benefit because widgets will updated and new one are created, and the developer does not need to concern about licensing structures for small bits of code.
The challenge will be determine the kickback price especially if the widget or module is create by contributes of others.
Like we already discussed, we are working on a way to make this all easier. First contributing to other content is a lot easier (without needing to send a ticket, testproject, etc.) since we introduced GitHub. We are slowly pushing all our content to Github at this moment.
All the contribution from a developers perspective will be measured and we are going to work on some kind of contributors list in the App Store (and eventually Mendix overall). We are also working on an incentive from a partner/company perspective as the total of all the developers within that company. Both are items on the roadmap so I'm not sure when this is fully implemented but I'll keep you posted.
You're right that placing the content under promotion is the only way to commercialise your content. This is definitely something we want to support in other ways. Also working on that, thanks for your suggestions. Very good feedback!