Marvinq bought a Samson SR850 some months ago and it looked almost exactly like my AKG K240 Studio! And at a third of the cost of the AKG! I'd say the Samson is a good buy.
Personally, the AKG 240's are the only headphones I will do a rough mix on. They say the Audio Technika ATH-M40fs (and M50) are also good cans to mix on, but let's always reference a mix on a good pair of monitors. For one thing, stereo imaging is a bit exaggerated when using cans.