I will be seeing Nick Jonas soon in concert and they have this deal for $400 where you take a professional individual photo with him, along with getting a designer bag signed by him, more things signed by him, a VIP pass and more. I think it's a good deal!
It depends on how you value that $400 dollars. I would not pay 400 for only a photo and autograph. I would pay a bit more if the offer was to have a 1 on 1 lunch time with em so I can pick their brain and get to know em better.