As to the anonymous comment, remember that prices isn't a function of production expenses. It's a function of perceived demand. Disney's charging $25 per hat (or whatever the price is now) because it thinks a significant number of visitors will pay that. (It's kicked off the project by giving thousands of ears away free to media and to annual passholders to in an attempt put enough ear-wearing people in the audience on any given night to entice others to buy a pair, too.)
I suspect that the tech cost of each hat is pretty trivial - the big expense is with the R&D and backend stuff, much of which is sunk cost at this time. So the question really becomes - "How much must these ears do before you'll pay $25 to buy a pair?"
Looks like I'll be checking out the show with a camera and looking at the IR signals!
I think that they should be part of more shows like Disneyland's fireworks and Fantasmic. I wouldn't mind if they were incorporated in the dark rides as well but not at their full intensity. we know they can dim just looking at the videos. I also like how you can sync your ears colors with a friend so you all can pick a color and find each other in a crowd. I think the next step is motion sensitive. If you jump up or down a lot they should change colors faster and then slow down to a stop when stationary, tilt to your side and one ear changes colors but not the other and so on. The technology is already in the Wii remote just got to incorporate the programming.
Perhaps bringing back those buttons as an alternative would be nice (though I think they were not that much cheaper).
Disney money aside, $25 for a Mickey hat is not that steep compared to some of the other ones that Disney makes.