Currently a very important forum thread is live on Moodle forums about having a premium plugins and themes section. The thread was started by Justin Hunt and involves active replies from Martin Dougiamas, David Mudrak, Gareth J Barnard and other fellow moodlers.
The forum thread is basically a discussion about having a premium subscription model for plugins and themes based on the popularity, number of installs, number of ratings etc.
There are many moodlers who are in favor of having a premium subscription model but many are also opposing it as Moodle is released under GPL and people are using it because of “free of cost” tag.
You can also join the discussion here: https://moodle.org/mod/forum/discuss.php?d=314916