might check out exile choppers site..
seems like quite a few of their bikes I have seen have this setup.

I saw a guy in Fayetteville with the custom cycle controls setup and asked him about price.
He said "it's one of those things that if you have to ask how much, you can't afford it" then told me it was upwards of 2 grand

 

Check out Moto x for the internal throttle set-up.

http://www.motoxcycle.com/internalthrottle.html

 

Here is the page from exile that has the internal throttle and twist clutch.

http://www.exilecycles.com/index.php?section=37