they are really quite expensive - anyway, comparing with the other
sollutions. Although it is possible to choose midi with better resolution,
I don't know if the resolution would be better as with hid devices
(probably anyone else has the answer to that).
I believe you can find alternatives to those here:
http://infusionsystems.com/catalog/index.php
Although expensive, I am not totally sure of this but I believe the great advantage of I-CubeX is that their sensor's signal can be easily
converted to MIDI which makes them very easy to use in any kind of software,
including PD.