Infighter vs Gunslinger

Infighters:
Advantages
-VERY high hp, as good as warriors in fact.
-Very decent damage
-Versatile (Like a bandit crossed with a warrior)

Disadvantages
-Crappy Range, worse than fighters and pages, not so sure about bandit tho...

Gunslingers
Advantages
-Very long ranged, better than bowmans and sins
-Can use elemental attacks at 3rd job

Disadvantages
-Crappy damage, worse than assassins.
-Very Expensive Class (bullet are kinda rare, the high level 1s)

Note: Don't judge me too harsly, neva played a pirate before, I've only SEEN how it is played.

None of your points make any sense. Infighters have less HP than warriors, the HP difference should be 3-4k at endgame levels. Decent damage can only be so decent; decent means it's not that great but it's not bad. And they don't have crappy range, most of their skills have more range than Bandits, and a lot of their 4th job skills are on the level of Boomerang Step in range.

I don't know exactly how much range Gunslingers have, so I won't debate you on that. It could be the same as bowmen, it could be the same as assassins, or it could be slightly more or less than either. And the last two points...what the hell? Assassins are one of the strongest classes in MapleStory (in terms of single-target damage, anyway). And those bullets are cheap, and they're pretty common. Weak classes are never expensive, by the way. They're not all that bad.

It's fine if you haven't played a Pirate before. Most of us haven't. But at least do your research.