It's not that it is over-priced. If all is fair, Playstation Move with several controllers/peripherals/etc can be pretty pricey, likewise with the Wii. I would even go as far as to say that Kinect may be the cheapest full motion control setup of all three consoles. (Including Wii). Think about all the peripherals and miscellaneous BS you can purchase for the Wii/(And most likely PS3). 4 Controllers with Motion Plus? Can be pretty steep.
However, Kinect does have the 'biggest' entry point number tied down to it. (Which is the real number that matters to a majority of consumers IMO). It's very similar to the 360/PS3 battle earlier this generation IMO. PS3 had tons of value and a lot of stuff packed in (Wi-Fi, Free Internet, Backward Compatiblity, Blu-Ray, etc) (Just a few years of Xbox Live alone covered the difference in entry costs for PS3/360.). The problem was it's entry point price. The PS3 people liked, desired, wanted, etc but it got cannibalized by the 360 regularly because it's entry price was just too much.
The other problem in my eyes is quite simple, Kinect will have a lot of pre-emptive hype. Something of this sort always will and always does. It has exciting possibilities and looks like something straight out of a Hollywood flick. This pre-emtpive hype will even get a decent amount of people to 'Jump In' and pay the $150. The problem is without compelling software, this hype could actually work against it.
With these pre-existing problems / conditions you are looking at a tough sell. The software isn't there yet by most accounts (And may never be). With reports of it's lack of accuracy/precision/etc/Potential to not be played while sitting/ 2 players at once only.... You are looking at early adopters dropping a the largest 'entry' price of all three motion control setups, for a lineup of limited software, possibly full priced games, with possible spotty performance? Recipe for disaster. Word of mouth is what will make Kinect sell and without that low entry point or killer application or really amazing performance, I don't see the word of mouth being overly positive.
