Quoted $300+ from dealer shop which I know a serious rip-off price for mere carbon filter.
Searched eBay, local stock comes with some $100 price tag, still too steep.
Found a German seller, selling compatible filter for approx. $27 for the item and $15 shipping – even made in Germany!
The confusing part was finding b250 cabin filter replacement in YouTube resulting the previous model, W245(2005-2011).
Any 2012~ model need to search for W246 instead, like this.
5-10 minutes work, don’t even need a screw driver. Boom, saved $250+.