depends on where you go.
Lethal Force Institute, Gunsite and Thunder Ranch are all very much worth the money.
I wanna go to Lethal Force Institute as Massad Ayoob is the man.
I dunno how MA is, but in TN we have to take a concealed carry course from a state licensed instructor.
Even if you do go to a school, I'd recommend at the very least picking up a copy of In The Gravest Extreme by Massad Ayoob. It's an excellent read on the topic of concealed carry and self defense shootings
here, about the author
http://en.wikipedia.org/wiki/Massad_Ayoob
he frequently fills the role of an expert in defense shooting trials.