I'm thinking about selling my Beyerdynamic dt770 (80 ohm). They only have about 5-10 hours of use and will undoubtedly exceed your needs of deep bass.
I still haven't made up my mind about selling them though.
They are awesome headphones.....but so are my dt880
I got the 770's for doing vocal takes with....and even though they sound way better than my hd280's and are extremely more comfy, the 280's isolate a bit better and also boost the presence of the vocal....so I feel like I sing better with the 280's on my head.
Anyway, if I did sell them, I might let them go for $120.
Still undecided though