In a bowl, toss together popped popcorn, cereal, and peanuts. Set aside. Butter sides of a heavy 2-quart saucepan. In saucepan, combine apple juice, sugar, corn syrup, vinegar, and salt. Cook over medium heat, stirring constantly until sugar dissolves and mixture begins to boil. Cook to hard ball stage (250 degrees Fahrenheit on a candy thermometer). Remove from heat. Pour syrup over popcorn-cereal-peanut mixture; toss to coat. Spread in a buttered 15 1/2 x 10 1/2 x 1 inch baking dish. Cool until hardened. Break into pieces.
*1 ounce of unpopped popcorn kernels (2 Tablespoons household measure) makes approximately 1 quart of popped popcorn.
**3/4 cup apple pop wine may be used instead of apple juice.