Ah headsets..........
Some pinch, some fall apart, mics fail, gel seals leak.
DC's everytime - I got a pair second hand from ebay 6 years ago for my CPL IR, instructed with them and have flown turboprops everyday for 4 years. All I have done is replaced the gel seals after they slimed me (although the ear-cup knickers captured most of it).
David Clark H10-60 : David Clark - Airplan Flight Equipment
Less than half price below:
David Clark H10-60 aviation headset perfect condition - eBay (item 290517606507 end time Dec-31-10 18:20:46 PST)
Sennheiser are good value but pinch my head after an hour - but that is just me.