Of course, it will have to come down farther if video game manufacturers are going to consider spending $ developing features for people using these. Right now, spending time designing a game for this kind of interaction means you'll be able to sell it on the Wii.
When the PC, PS3, and XBox start having these kinds of input devices, game (and software) manufacturers will take much more notice.
Ah, I'm blind. For $100 it's well worth it. It's completely different type of interaction, true 3D (actually 6D as you get also orientation). I would get it even without games, just for hacking.
I used to play with Ascension's Flock of Birds [1]. You can get pretty accurate 3D position and orientation.
Though these older systems were pretty expensive (~$10K), I wonder what would be the price of these new toys.
[1] http://www.ascension-tech.com/realtime/RTflockofBIRDS.php