I would buy one! Absolutely! But I just don't think anybody around here can produce this board for a competitve price.
Here in germany the Nunchuck is ~ 20 Euro. I would throw in another 10 Euros because I appreciate the whole idea of open-source hardware. So I would be willing to spend 30 Euros for the 3-axis accelerator shield.
But just this morning I stumbled across the Ethernet-Shield-Kit from adafruit and it sold for 15 Euros (without the Xport). If the LIS302DL boards go to similar prices (15 Euro + the chip) I think you are already past the maximum limit.
Not mentioned yet : postage+package ; Board is not assembled? I can't solder SMDs, I'm too old for that :-X
I find everything in this thread very promising, but its really hard to beat the nunchuck ...
Eberhard
At Digikey, the sensor is $7.70 when you buy 100. Add a few square inches of PCB and some support components, and a level converter. I think it can be done for well under 30 Euros.