So its time to discuss hype versus actual value, when deciding which comics you want to collect. This is a very subjective answer of course, as we all have different tastes. However, one thing should be considered when you are deciding how you want to invest that $50 that is burning in your pocket. Specifically, I am speaking about a comic title's origin.
Origin in the sense of how did the comic story begin. The comics that have their birth in TV, Toys, or Movies, do not stand the test of time, compared to those comics that started purely in comic book form. So while Star Wars, Halo, Transformers, and G.I. Joe are hot titles and characters right now, they did not get their start in comics. This is a big determinant in whether a comic will keep its value over the years, as the fans of these titles grow up, and the captive audience has moved on.
Lets compare two titles. Star Wars and Teenage Mutant Ninja Turtles, two hugely successful franchises. Both have had movies, t.v. shows, toys, video games, and of course comic book representation. But which of these comic titles has had the more impressive comic value over the years? See Comparison below of original issue # 1 value as of today in Wizard Price Guide as of 3/2008.
TMNT # 1 -- Mirage Studios -- $900
Star Wars # 1 -- Marvel Comics -- $30
Now, there are a lot of factors to the price difference, including scarcity, perceived value, etc. But, characters that have their origins in comics versus other media, largely outweigh those that do not.