Plan on buying a 2009 328i but...

Heard maintenance is exspensive, especially because it isn't certified.
Never had a BMW before but i just need some general info on what im getting myself into..
any help?

I would not let maintenance deter you from making the purchase. Now, if you were looking at an M series car, a little different story. Keep in mind, with 15k between oil changes, it actually works out to be less per mile than your civic is...and you dont have to physically go to oil change place every 3k miles . Yes, brakes are more expensive, but they are awesome brakes. I had a tahoe once, and looking back on the fact I would go sit at oil place every 6 weeks is crazy. I just picked up a second car (2009 328i)...I just love these cars, they speak to me every time I hit the start button. If you can identify with this last comment, it is time for you to double your efforts and find your new baby.

Also most people that want to keep there cars a long time will follow the Mike
Miller old school maintenance schedule and change there oil every 7500 miles or
once a year. google Mike Miller BMW

Tires are expensive especially if you stay with the run flats.
Battery's are also expensive.

Your response is much apreciated

Thank you so much for your response.

FWIW, the 328 with MT is probably the most trouble-free 3 Series BMW makes. Obviously, much would depend on the care any car was given if it's purchased used.