For a serious study of Raja Yoga, here is a set of 56 lectures on Chapter I of the Yoga Aphorisms of Patanjali.

It's a marvelous collection of talks, and carries our return privileges if you aren't satisfied. The CDs come in a handsome case that holds all the CDs.

There is also a four -lecture summary on 4 CDs of the same first chapter available.

Please note that the CDs come from Australia, so it may take a month or so to get more if we are out of stock.

In May of 2005, the Vedanta Society held a retreat with Swami Sridharananda on the practice of Raja Yoga.
You might also like to investigate the set.

Sw. Sridharananda's talks have always been well received not only because of the quality of the talk, but his very clear speaking style that is easy to understand.