I recently modified a pair of Sennheiser HD25 to increase both isolation and comfort. I documented most of the changes in this thread:
The whole reason I modified them was for my plane ride to Europe. I'm back now, and I don't have any other long international flights planned soon, so I would like to sell these. After I made that other thread listed above, I spray painted these black, coated with a glossy polyurethane, and epoxied the wire entries closed to increase sound isolation. The isolation is now nearly as good as etymotics with triple flanges, and the comfort is miles better than the etymotics. Comfort is better than stock HD25, but not nearly as good as, say, Denon D2000 or Senn HD800.
These will come with the modified headphones, the two sets of original pads (cloth and leather), the original headband, and the original cable (I have used an old Grado cable on the modified headphones). I have the original box, but I will not be including that unless you request it because it will make the package bigger and increase shipping costs. I can make you a silver cable, too, upon request.
Price is $155 plus shipping.
Edit: Forgot to mention Sennheiser carrying bag will also be included. Basically all original accessories minus the box, which can be included upon request.