Microsoft did not unveil the price for Kinect at the E3 2010. They only said it will launch on November 4th. The price for Kinect now appears on Walmart.
Walmart sets the price for Kinect to $149.96. You can actually pre-order it on Walmart already. Kinect should ship on November 4th says Walmart.
GameStop is also already taking pre-orders for Kinect at $149.99.
Amazon has not published a price for Kinect yet. They do not offer pre-order yet.
More details about Kinect.