E90 FREAK you need to hit me up brother. Like Volasko said we have an electric water pump. Whatever you do dont buy anything from the dealership except the 50/50 coolant which cost $27 (here in IL). Check out the DIY we have here coz thery're pretty legit. The thermostat and the waterpump are at the bottom of the car not too far from the radiator. My dealer her in IL (Knauz BMW) quoted me $2500
for parts and labor. Like I said follow the DIY we have here and if you need help let me know so I can walk you through it.
FYI I bought my thermostat from autozone for $171 and my waterpump from partsgeek.com for $315 including shipping handling and insurance.