I had the same thought about somehow using AI to make this completely automatic and increase the quality of the story. Turk does have the ability to allow workers to upload files so producing binary data like images or videos is definitely possible.

As for the cost, I was following ProPublica's advice. Apparently workers assume that less expensive jobs can be done more quickly, and if you make them too expensive the process can actually take longer:

http://www.propublica.org/article/propublicas-guide-to-mecha...