Start with 'Free'!
If you're not sure where to start, the FREE eBook, 'The NLP Eye Accessing Cues' The Not-so-Hidden Secrets Of the Mind, might be a good place. You'll get this by subscribing to MetaMoreTalk, my eZine on the right.
Then, it depends what your goal is:
If you're more interested in how you communicate with others and how to be more influential in your work and personal relationships, then
is the way to go.
Either way, you'll get great value for money and tools you can use immediately to enhance your life.