I got some of them through the library. Maybe it was because it was out of order, but I didn't enjoy it enough to really adopt it. I think it might be a little out of date by now. I remember his methods of dealing with negative memories ("swish" pattern, I think he called it). It doesn't seem to be nearly as powerful as the New History Generator or the Belief tape.
Personally, I think Belief is underpriced. It's powerful enough to be called "New Belief Generator," and it's one of my favorite tapes because it works on a level above that of either behavior or perception, becaus belief orders behavior and perception. Plus, I always imagine my cats as being the baloonists in the story, planting catnip seeds. It's a charming mental image, a Persian and a Himmalayan batting and biting at cords in order to pilot a hot air baloon down into places where they can plant catnip seeds.
I do like his reductionism of behavior into the pleasure/pain principle, his enthusiasm, and his clear sense of purpose which shines through. Robbins strikes me as a pretty decent, honest fellow.