Thief of Thieves and Revival already in pre-production; both have gone way up in less than a year of being published, but still very low production numbers compared to Marvel and DC. If Walking Dead #1 is a $1500 NM book, then buying ToT at $60 and Revival at $15 is still worth the price. I've heard Chew is in the prcoess of being made into a TV series, but I honestly don't see how it can work as such; amazing writing, but just too "far-out-comic-booky" to me.
I think quite a few people on these boards have said it and it makes perfect sense; Load up on any Image Comics #1 that is on the rise; they are very low production with way, way better writing than DC and Marvel these days.
Walking Dead #1 was $3 in 2003, now $1500
Chew #1 was $3 in 2009, now $450
Peter Panzerfaust #1 was $3 less than a year ago, now $115
Thief of Thieves, Revival, Saga, Manhattan Projects, Fatale = Currently high dollar but initially cheap investments
What's next? Nowhere Men, Bedlam, Happy, Clone, Todd the Ugliest Kid on Earth (I agree with Indy, I like this one)
I feel like you could perhaps double your money on key Marvel first appearances that are coming out as movies such as Thanos, Mandarin, Winter Soldier(Bucky), Malekith, Electro (Jamie Foxx playing a formerly caucasian villain?), etc. Nonetheless, just see what solid Image #1's are doing, and more improtantly, pick up the first few issues and read them yourself to determine if they have great writing and lasting power. Good luck, let us know if you dive headfirst into a certain series.