How can i tell if a comic book is fake?

ok so i want to know how i can tell if a comic is fake. i want to but a No 1 issue of superman from Action comics. I'm sure the one i looked at was a reprint but it was going for around 250... but the 10 Cent sign on the front looked different than the other pictures iv seen of the comic.. it looked longer and bigger. it started from the "S" of comics and went all the way to the right of the page.. it looks different.. but i don't know if its like fake or whats the deal with that.