Hi mm718,
If you're looking for an ebook, I would recommend Dr. Hanscom's book. Unlearn Your Pain is a workbook with lots of space for structured writing exercises so it makes more sense in th paper version (unless there is some equivalent for how to do the writing exercises in the ebook version, I'm not sure).
I found both really helpful. I read Dr. Sarno's books first and he is clearly a visionary but was writing at a time before there was much scientific evidence to support his ideas. For me, I really need to understand the evidence behind something in order to believe it. If you're looking for something similar, Unlearn Your Pain and Back in Control both provide a great overview of the science supporting Dr Sarno's work. I found them both very accessible and readable too. Dr Hanscom writes about his own experience with TMS as well, which I appreciated.
I'm not sure if you've heard of the Curable app yet, but I've been using it & really liking it, it combines a lot of the ideas and exercises from all the TMS books.
Let me know if there's any other info that would be helpful