How much better could it sound for 30k? I have a $35 headset and it works just fine.
When you go from hearing sounds that come out of a narrow tin can, to literally being on stage with the musicians...we'll talk.
Here's my method on buying anything electronics: more bang for your buck.
So for example if I bought a 120GB SSD at $120 bucks, that's $1 per GB. 240GB SSD at $420 is ~$.57 per GB. Video cards it can get a little more trickier as far as how much you can overclock and push the voltage, what performance you are pulling in comparison to the next higher card.
Headphones, well I can only say a few things. What sound signature? Laid back? Over-analytical? Brighter highs? More extended lower end? Thick mids?
Since I listen to pretty much all genres of music, I had to compromise slightly to make sure all of them sound great. However my headphones knocked the price down to $699 which was a steal. It is pretty much the best value right now as a genre "master". Dark headphones though and the treble does roll off...I wish it sparkled to be honest.
Also source is important. You ain't going to get good sound coming from an iPod. My cans need an amp.
Even these Sony's I just bought, I can't even get my SanDisk Clip+ to output enough power to drive them, so I have to carry with me a portable headphone amp. And really 63 ohms, and still not enough juice? It's bizarre. I think my player is busted.
Then the quality of the song files. Lossless or bust. 320kbps is about the least I can accept, but only for recordings I can't find lossless for.
So you have two things to consider, headphones and the source. At the most basic. Then you can split hairs all you want. Like getting an 18" Optical cable cause it sounds better than 3", 6", 10" etc.