Grease two 13"x9" pans with cooking spray and set aside.
Pop popcorn, yielding about 14 cups. In a very large bowl, combine popcorn, oats, almonds, raisins, cranberries, and sunflower seeds. Set aside.
In a small saucepan, combine honey, brown sugar, and salt. Heat over low heat until brown sugar dissolves, about 5 minutes.
Pour sugar mixture over popcorn mixture and stir well. Pour half of the coated popcorn mixture into each of the prepared dishes. Lightly press mixture into pans using lightly moistened hands or a piece of waxed paper.
Chill in the refrigerator for 30 minutes, or in the freezer for 15 minutes before slicing into bars with a serrated knife.