In headphones, you get what you pay for. If you have $30 hearing....buy a $30 set of 'phones.
The Headroom site that Dave N quoted is a good place to start. They know audio....headphones and high-end. Their headphone amp packages are some of the best to be had.
Stay away from Crutchfields, they have become the mailorder version of Circuit City. They sell a little bit of everything and typically know a little bit of nothing about it. No high-end to be found there....just lots of mid-fi trash.
You won't find a truly good sounding wireless pair of headphones. Put up with the cable if you want the best sound.
If you are looking for muff-type 'phones, I'd suggest certain models of Sennheiser. If you lean to the earbud style (my own preference as they're lighter, more accurate, and seal out all extraneous ambient noise) ...then Etymotic Research is difficult to beat. Careful matching required, though, if you're buying for un-aided use with an iPod or similar.
....BH