There are a number of places online that offer rebuilt units for less than half of that price but it is for the unit only. Google for rebuilt Eaton supercharger. No labor. Did your $2k include labor? Check the fine print, but a number of sites offer lifetime warranties.
I believe these cars use the Eaton M45 supercharger, so you may not have to buy one that is listed for Mercedes and pay the Merecedes surcharge. GM and Ford have been using these Eaton superchargers, too. There was a post from someone recently that said they thought the C230 used an M62, so double check which it uses first.