I'm not interested in iOS development, so take this with a grain of salt, but I think it should provide a brief introduction for free to allow people to evaluate it. Also, I assume it's possible to upgrade packages by paying the difference?
Of course, samples are available! Here they are: http://diveintoios.com/samples
In the meantime, please use the direct Vimeo links:
Basic Package: http://vimeo.com/30582950 Premium Package: http://vimeo.com/30583073 Complete Package: http://vimeo.com/30583124