I can say for sure that not everyone prefers neutral headphones. How do you explain the people who like LCD2s and 3s? The Audez'es are definitely not neutral, yet they're loved by so many people. Many of the TOTL CIEMs are definitely not neutral, but they're more popular than the CIEMs tuned to be neutral. Well I don't want to generalize bassheads, but I think bassheads consider themselves bassheads even though they listen to headphones. Some people appreciate the quantity over quality. It's good to have choices, isn't it?
Anyways, CPTBadAss,
ATH-AD700 - $100 - Spacious, open headphones. Fairly neutral, bass-light. Would probably be great for orchestral or instrumental music. Never heard it myself, so I can't say for sure. The headphones and pads are huge though, so it might not fit everyone
AKG K701/K702/Q701 - Slightly less than $200 if you buy used - Kind of similiar sound signature to the AD700, but slightly brighter and has better dynamics. Has velour pads, so they're very comfortable in that respect. The bumps on the headband might be uncomfortable though.
Hifiman HE-300 - Currently $100 @ J&R and out of stock, but you can still place an order - Warm and smooth sound signature with rolled off treble. Stock cable is microphonic though.
HD 598 - Can be found for less than $200 used - Mid centric, slightly bright. Low on bass impact.
DT 880/600 ohm - There's one on head-fi for $200 right now - Neutral, slightly bright. Best used with tube amps but might be driven fine with your cmoy. Extremely comfortable. Probably the most detailed out of everything here, along with the AKGs. They're fairly "fast", so they'll be great for metal along with the brightness.
Grado SR225i - $200 - An improvement over the sr80i but 2x the price. These will satisfy your metal cravings.
If we take into consideration closed headphones, then we can add:
dt770/80 ohm, ATH-A700X, and possibly a few others that I can't think of atm.
I hope that helps!