Still have the same pair of DC's I bought as "nearly new" second handers seven years ago and they still perform well on shortish flights. Anything 1hr+ and they become a little irritating. Now use them as a back up or for my ususpecting pax
Invested in a pair of Lightspeed Zulu's back in the summer and love them, especially the ipod connectivity which i've used several times when flying as rear gunner. The blue tooth connectivity is however useless. Tried to use it on a recent 4hr trans euro flight and only picked up a signal when in the circuit at the destination! Would not actually use either function if P1 ing as probably a bit distracting.
One obvious tip at the moment is to look at exchange rate disparity. US bargains are probably over. I'm currently in South Africa and bagged an ICOM transceiver for a bargain price when the Rand was 17.8/£1. Also a lovely mornings flying out of CPT for just over a £100 quid!