Popcorn is a super healthy snack (as long as you don't drench it in butter or salt)!
Here is what I recommend:
1. Get an air popper- they cost around $20 or so. You will end up spending less than if you were to keep buying the microwave popcorn. You get no added sodium or fat (except for what you add).
2. 1 cup air popped popcorn has only 20 calories and 7 g of fiber and 4 g protein! You can't beat that! Most people would eat about 3-4 cups which would give you- 68-80 calories, 21-28 g fiber and 12-16 g protein! Not bad. And, because of all the protein and fiber you feel full longer.