I went to Ronnie Nunn's "Nunn-Better" camp in 2003 and to Phil Robinson's Pro-Am camp in 2004. Both were in Orlando. The Pro-Am Camp is basically the same in style, content and skill level as Nunn-Better. But when Ronnie was hired as Supervisor of Officials for the NBA, he had to stop using his name to promote the camp. At least, that's what I was told.
Each camp was about $525. That included hotel, but not food. Most of the games were officiated at Disney's Wide World of Sports Complex.
The instruction is fantastic. The observers are all NBA officials. The feedback is less than spectacular. Let me clarify that. The "in-game" feedback (critique) from the observers is generally very good. But there's no feedback about how you performed overall at the camp. I was very disappointed in that. I didn't like Phil's camp quite as much, for a couple of reasons. Still very good instruction and probably worth your time, tho.
Here's the thread about my trip to Nunn-Better:
http://www.officialforum.com/thread/9469