On ebay you can search for ended listings and that is a lot more meaningful because people usually snipes ebay auctions.
For example you have here a sensor ended yesterday at $176:
http://cgi.ebay.com/Brand-New-Kinect-Sensor-with-Kinect-Adventures-/170566027858?pt=Video_Games_Games&hash=item27b6870a52
and here a $443 250GB bundle:
http://cgi.ebay.com/BNIB-Microsoft-Xbox-360-250GB-Console-with-Kinect-/140478146437?pt=Video_Games&hash=item20b5266785
Now the funny thing about ebay is that prices quckly levels between them, because for this kind of product ebay behave very close to an ideal market (perfect competition). So you can assume that that is the quotation for these items on ebay. Is higher that the store price and this confirm that the item is selling out almost everywhere.
On a side note you people are largely overextimating this ebay speculation thing, because the number of the kinect sold on ebay is under 5000 for the US site. That is very little compared to the shipped quantity.
