Not exactly but ... But you can look at the WordPress plugin market - the original concept was 'donations' i.e. pay as you like, but many surveys of plugin developers show that the number of donations is minimal, averaging at 8 donations and $50 cash. Take the average development effort in a plugin, and that works out at a developer rate of $0.01 per hour.... The whole Wordpress market is moving rapidly away from free / donations to either 'premium' ( e.g. codecanyon ) or 'freemium' where the free offering has a paid for offerng that extends the features. ( The abandonment rate by the developers of free only plugins averages 18 months ) So at least for the 70+ million WordPress sites, the pay what you like experiment has failed.