There are only two endorsements from Rand of presentations of her system: the first, for Nathaniel Branden's Basic Principles of Objectivism (now in print as The Vision of Ayn Rand). The other endorsement was for Leonard Peikoff's course, The Philosophy of Objectivism.
The Peikoff course The Philosophy of Objectivism used to be available from the ARI Bookstore. As of last September it was listed as "out of stock."
I have suspicions about why it's no longer in stock -- because of discrepancies between material in it and later material by Peikoff, for instance in The Logical Leap.
Coincidentally, I decided last August to purchase the course. I'd blown hot and cold because of the price and had never quite made my mind up to spending $240 for it. But then, due to issues which arose on ARCHN, where I was posting for awhile, I decided to spend the money so I could check what Peikoff said -- and Rand endorsed -- on "certainty" in that course. Just then we had trouble with our Am Express credit card -- some identity-theft charges. During the week I was waiting for a new card, the course went "out of stock." Rats.