NM 98 sells because of the imminent movie and Deadpool's appearance in the first Wolverine movie. A character's other media appearance can be attributed to many of the copper age rises in the past few years. Until you hear about that movie featuring Nightwing, the supply of Tales of the Teen Titans 44, which is large, will keep the prices tamed.
I don't entirely agree with you - to many people, Deadpool is an interesting and attention-grabbing enough character to want his first appearance. I will agree that the prices are higher because of the movie links, but the book would sell regardless. I bought the book because I think the cover is badass and it was on a list of keys I wanted, with the added bonus of it being a good seller.