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Depends on the game. If the game uses two analog sticks or one analog+dpad at the same time, there's no way you can use it to play with. If it just uses one analog or just the d-pad, then yes, you can use it. Arcade sticks, as their name suggests, are best used for games you would typically see in an arcade. For most modern games, you might as well just use the default PS3 controller.
On a design level, yes the fightstick was designed purely for playing fighting games but it doesn't mean you can't use it to play other games as well.
Now the price isn't because of versatility reasons, but more about quality reasons. It might not seem like much to you, but to people who invest at least a couple hundred hours into SSF4, the quality of the buttons/sticks means a whole lot. But like I said, if the game does NOT require you to use more than one analog stick at once, or a combination of analog+dpad, then you can use it to play that game. I've personally dicked around with FFXIII with it, and while it's a bit awkward at first, it's playable. The fightstick shines more with arcade-style games, so something like Scott Pilgrim would be amazing with it.