Wow, that is really cool.It's time to update my Nexus One to Android v2.3.3.
Yeah I know it looked incredible, but did you see the price for one ?!? I think it was something like 400$, a bit pricey in my opignon.
I think it's aimed more at the developer who can afford it and write it off come tax time. Still, it's cool that they even have something like this...you could always get the ioio board though... :)
You can use a normal Arduino Mega, Uno or Freeduino instead. All you need is a USB host shield and some sensors and actors. Should be easy to build your own board. All software and firmware for the Arduino needed is included in the ADK