Adorama has the Sony MDR-7506 Professional Folding Headphones for $100 - $20 off in cart = $80 with free shipping. Features 10Hz - 20kHz frequency response, 63 Ohms impedance, and 40mm driver unit.
I find the high end on these headphones to be quite shrill, almost painful to listen to for me for more than 10-30 minutes without equalizing. For some (those will upper end hearing loss) this may be a good thing, but if you're sensitive to high frequencies, the ATH-M50 would be a better buy. These are good, analytic headphones, but I'd recommend trying them before buying if you're going to use them regularly, otherwise the high end can be painful.
How does one fold professionally?
I find the high end on these headphones to be quite shrill, almost painful to listen to for me for more than 10-30 minutes without equalizing. For some (those will upper end hearing loss) this may be a good thing, but if you're sensitive to high frequencies, the ATH-M50 would be a better buy. These are good, analytic headphones, but I'd recommend trying them before buying if you're going to use them regularly, otherwise the high end can be painful.