Hi,
I've tried a few prostate massagers over the years without much success. Sure, they feel good, but I've never managed to have an orgasm solely from one of them.
However, I'd seen some videos online of people using a back massager called the "backnobber". It's a curved bar with a ball on the end that's used to massage your own back. I found one on Amazon and bought it. The very first time I used it, I had a hands free orgasm that was so strong it was almost unbelievable. With very little effort and only about five minutes I was in heaven. I can't recommend it enough.