USB Blue-Tooth Headsets

The Smartboard software that I use in my classroom allows you to record a
screencast as you manipulate the Smartboard, essentially creating a
vodcast over your class notes.  However, right now I only have an
old-school USB microphone and I want to upgrade to a hands-free USB
Blue-tooth headset so that I can stand in front of my SmartBoard and
manipulate slides while talking and recording a vodcast.

Is there a Blue-tooth headset you like?  Are you experienced with one in
particular, and would you recommend it?

I have some cash coming to me from a grant, so money is not an object as
long as I'm below $400-$500 or so. 

Thanks,

-- Doug