Over the years, I have been asked many times whether a certain comic is collectible ... that is, will it go up in price?
If you are thinking of "investing" in comic books, your thinking is flawed. If the economy gets really bad, just like any commodity such as real estate or stocks, you may not be able to sell them for a high price very quickly.
Buy comic books that you like and can afford. If you eventually make a profit on those comics, then you have doubled your enjoyment.