The INTERIOR carbon fiber trim, option code H73, is $950 USD.
The EXTERIOR carbon fiber trim, option code 773pkg, is $3700 USD.
Not sure where the $2300 came from. Perhaps they clicked on the wrong line item in the MB online ordering system. The only thing that is close is the 320 Multimedia Package that the Order Guide shows as $2300 but my dealer said that the current correct price is $2370.
I think that he might be from Canada then because I could have sworn that I once saw the interior Carbon Fibre trim costing 2300 here in Canada either that or the dealer accidentally gave the pricing for the recaro seats not carbon fibre