In a previous post, we mentioned that we were examining our commission structure. Today we published changes to the Mechanical Turk commission structure for Requesters. These changes will help allow Amazon to continue growing the Amazon Mechanical Turk marketplace and innovating on behalf of our customers. The current pricing will remain in effect until 11:59 PM PDT on July 21st, 2015.
You can learn more about these changes here: http://requester.mturk.com/pricing.