It's not like they hold you at the door and don't let you leave until you sign.

They tell you up front how much it costs, and I didn't find it high pressure at all. It was an awesome experience for my DD and I don't regret sending her on both her trips at all.
I do know that her teacher did nominate her, and I do know this teacher did not nominate everyone. She also had to do an interview before she went. It probably didn't matter since they wanted my money anyway, but the interview was a good experience for future job interviews and also interviews she has had for groups she wanted to join in college.
Like I said before, I know from previous experience that it is an amazing program and if you have the money, I say go for it!