If you're gonna do it, save up a little more and go for the dogs b*ll*cks...Sennheiser or Bose....I used to use the cord versions when I was sound engineering and they had gorgeous tone. I checked out the spec on their latest cordless and they've got exactly the same frequency range. You'll probably find that most high-spec cordless are as good as most medium-high-spec corded nowadays.
2 tips when buying headphones though:
1. Try them on. Don't buy blind (ie on the net) until you've at least tried a pair. make sure they're comfortable because after an hour's worth of use you'll regret it in the future (I have actually had blisters on and behind my ears from using cheap headphones at gigs - and it bl**dy hurts!!)
2. Listen to what you can't hear. The more sound they block out, the more effective they will be. Apparently Bose now produce a pair that block out 95% of surrounding noise before you even turn the music on! There's no point choosing a high spec headphone if you can still hear background noise - its like spending £2K on a pair of speakers only to have your wife or your mum pacing up and down in front of them playing a trumpet.
I guess it kinda depends on your budget - but if I were you, I'd wait a little longer and save up for the daddy's.