This will be interesting..... On a business level, sure I can see a device like this selling (with good software), for $25K or more. When it comes down to it, it's all about supply and demand. Business devices like this are not really around right now.
Now, for consumers, If it's more than $300, I wont get one... My guess with the Dev kit going for $3K (this price point would rule out most home users who just wanted to play with it). In the real world, for the first year, around $1500-2000. This price point will only sell to businesses. Consumers on a $2K "toy" (come on who is going to use this more than a toy or gaming at home ?), it wont sell very well at all.
Microsoft's best bet is to release it under $500, Give the dev software free with a plug in to current dev software so people can adapt to it easy.
Even if it was $99, if it didn't have any software and don't work on the xbox /xbox one, it would be worthless device...Might be fun for a few weeks to play with the demo stuff but once the thrill of owning and using it is over...it will look pretty on a shelf someplace and never touched again.
So when it comes down to it, it's about software support, then price.... It needs PLENTY of software for it before their is any real value to it. To be a HOT seller and sell thousands or even millions, that price/software needs to be JUST right.