Not to leave us totally putting down on TR - I found that his Personal Power series was very helpful (and motivating) and it probably gives you most of what can be gained from his products, if you had to only have one.
You could get a cheaper copy of the set through eBay, especially if you like working with audiotapes. But there are also deals on the CD version there.
It is also possible to find this set at some public libraries.
