I don't know if you could really call them headphones, but if you want something to tide you over while you save for something better,the Koss KSC75 are incredibly good for what they cost. Somewhat let down in build quality but the sound is great.
I recently got a Corsair HS35 Stereo, since I needed a pair of headphones with a mic for uni tutorials; they're quite nice, and under AU$100 ($69 at JB Hi-Fi). The mic's also detachable, so since I don't need it most of the time it's in my desk drawer.
Before this, I was using a cheap Sony pair, and that was decent too.