The interview prep folks get up to date feedback and intel on the interview process. They know what is required. They help you to organize and prioritize what you need to do, say, wear ect. Some people need the prep, some do not. I didn't use a prep company. My prep came from a failed interview a couple months prior to my Delta interview. I learned from the first one and applied my new found knowledge to my next one. It worked. Now I've been here many years. The gouge you get online may be fragmented and incomplete. The gouge at a prep company will be perfect. What's $300 when you have the potential to make so much more than a poor rj fo. Good luck in your flying career.