Try making popcorn with coconut oil. Not greasy, at all. In fact, you have to add a bit of melted butter or the salt will just go to the bottom of the bowl.
Try it once, and you will throw away any microwave popcorn you may have in your pantry.
The professionals (movie theater concessions) pop with coconut oil (you might find premade packs of the orange-colored solid oil at some commercial restaurant supply stores).
Do what the pros do: pop with coconut oil, and top with real butter.