This actually has been my policy since I got my first diesel. Every filter (oil, air, or fuel) I've bought for my M-B has been from a dealer (either Autobahn Motors or Smythe European), and every filter I've bought for my truck has been a Motorcraft.

That said, IIRC one of the filters that was torn apart to find junk in the bypass element WAS a filter from the dealer. I'm due for an oil change, and intend to open up the bypass element on my filter (purchased from the dealer for about $16) to see what's in it. If it's a proper bypass element, I'll get another dealer filter...if it's filled with waste cotton, seeds, bugs, etc, I'm finding a Baldwin dealer.