Not sure why no one mentioned the Sony Mdr-7509HD.
For that price range, they're a stellar fit. The bass isn't exaggerated, but it is very VERY brilliantly reproduced when it's prominent in the mix of music you listen to through them. Punchy hip hop tracks sound THUMPY. They don't add to the mix, but they give one of the crispest bass reproductions you can find at that pricepoint (in my experience).
The problem with gaming, though, is that a strong set of monitors that does music well isn't going to be what you want for gaming.
Gaming ends up needing overly exaggerated bass and highs, a mic (especially for team based FPS), 5.1 compatible (either through USB + 3D simulation software or via 5.1 jacks), and so on.
I use the Mdr-7509HDs for movies, music and production, and switch over to a pair of Roccat Kave gaming headphones for gaming.
They have a mic, three directional drivers in each cup for surround sound, incredibly heavy bass, and a box for controlling levels (mute for the mic, volume for each driver, master volume, etc).
Using the Roccats for music is incredibly annoying; it adds an extra depth that makes music sound a little too resonant, and the amplified bass is just silly. It really sucks for music. That said, stuff like approaching footsteps in an empty hallway, distant explosions, or the reverberations of empty shells hitting the floor in game sounds absolutely spectacular with these things.
For the inverse reasons, i don't game with the Mdr-7509HD. Aside from the absence of the mic and surround sound, it doesn't offer the same "depth" that you really want for a realistic gaming experience.
It really is comparing apples to oranges; The stuff you want in a good pair of gaming cups isn't at all what you want in a good set for music.
PS, if you end up going with two sets, i'd recommend the MDR-7506 to help save money. They're a bit cheaper than the 7509Ds, but still offer a great level of quality. Certainly not as punchy, but if the budget is tight they're a stellar second choice.
http://en.wikipedia.org/wiki/Sony_MDR-V6 (info on both the 7506 and the 7509HD)