I've done it, and I thought it was a blast.
Sure it's pricey, but it occupied the beginning of the morning for my non-diving wife an I, and she enjoyed it just as much as I did. I wouldn't say it was cheesy or touristy... it's just another way to visit an aquarium, and I wish more aquariums did this.
The staff at the MOC went out of their way to make sure my wife had a good time too, and one of the safety divers accompanied her on the public side of the exhibit, talking to her about what we were doing, looking at, etc.
Heck, think of the $200 dive fee as a donation to the Maui Ocean Center. They do a great job there, especially in that they run an environmentally responsibile aquarium.
I didn't bring my camera in the tank with me, but my wife shot pictures from the exhibition area. Some of them didn't turn out very well, but she snapped this one of my feeding Mrs. Piggy, the Spotted Eagle Ray.
Right after we entered the tank, we swam over the acrylic tunnel into the larger open area...
The aquarium diver (who's name I can't remember) spent a lot of time looking for shark teeth (he's even doing it in this picture!). I'd say we spent probably about 70% of the dive looking for teeth (you keep the teeth you find to take home). While neat at first, I was pretty content to just sit on the bottom of the tank and look around. He probably thought I was bored... but I was having an awesome time. If I went again, I'd probably mention that I had no desire to look for shark teeth, heheheheh.
-Brandon.