Don't know about the Note 3 ones (they may work, but not fit in the Note 4 pen), but Best Buy. If you can't find them, go to the Samsung Experience desk. They know where their stuff is. (BTW, 1 spare set and an extractor should come in the box, in a little clear plastic envelope. If you tell them that yours didn't come with one, you may get a set for free - just a thought.)