Marvel's never shied away from promo books, and the 1990s had some really interesting ones. To get this double-sided anthology comic in 1992, readers had to send in a Charleston Chew wrapper and $0.50. This book featured four short stories starring popular Marvel characters Wolverine (and Jubilee), Spider-Man, Ghost Rider, and the Silver Surfer.
This was at the peak of the speculation bubble in the 1990s, so I remember seeing ads for a ton of promo books being billed as special collector's items in order to make people think they'd be a great investment.
Spoiler alert: Almost none of these books are worth anything today.