It would be nice to see how much 1 credit costs before having to sign up. For example, over at PeepCode (http://peepcode.com/) I can immediately see how much a screencast costs without having to click around. Good luck with your startup.
You can also head over to the about page ( http://binarycake.com/about ) and see a list of credit bundles you can buy and the costs.
Thanks for the feedback! Jamie
That said, they're a firmly consumer-unfriendly model, for those very reasons. And even then, the "more likely to spend credits" factoid only comes into play once they've actually bought into the system - seeing that it's Yet Another Credit System can be a slight added barrier to entry.
Expanding on this, if every place I spend money online worked with its own "credit" system, I would have upwards of 20 idle balances of my own money earning interest for someone else. Not a very palatable future.