Cosmic Ghost Rider is hot. Carnage is hot again (building up to Red Goblin) so What If? Marvel did a Cosmic Carnage. I mean that would be the hugest thing ever right? Well they did.
Twice in fact. In Amazing Spiderman #430 (available on eBay) and Amazing Spiderman #431 (available on eBay) Carnage takes over Silver Surfer. The book is already pretty pricey with both books going for around $30 and up (#431 slightly more.) These books are getting more notice (the covers are shown below) with Norman Osborn getting the Carnage Symbiote in recent issues of Amazing Spiderman. Bt this is not the only appearance of the Cosmic Carnage that Marvel put out.
Cosmic Carnage also fought the Avengers in What If? #108 (available on eBay). Just a neat bit of history and with cosmic characters, and Carnage getting heat, worth mentioning.