PS2 controller that isn't painful?

Whenever I play an hour of Gradius V both my arms end up hurting in pain.  I don't get this with games that don't require as much rapid button-mashing (not even the Grand Theft Auto games, which are pretty button-mashy but not as perpetually as Gradius).  Is there a third-party PS2 controller I should look for that's a little more ergonomic for games like these?

Don't be such a pussy.

I recommend you /S/litwrists