Started with a second hand pair of DC's that I got for a steal from a mate trading up, replaced the mike and headpiece, looked like new and performed well. Then when I got a job, I've traded up for the Bose, specifically after seeing an AME who told me it was characteristic of pilots to be missing a certain frequency range!
Think it all depends on your disposable income and commitment. If your taking trial lessons and not sure, then get something very cheap or use club. Just a low hour ppl, not much disposable income then DC's do a great job. If you can afford the nice headsets and your committed then go for it. Take care of them and they will last you.