Hi Silencer,
Welcome to Head-Fi. As far as I can tell, the Sony MDR-V6 are NOT available in Australia. The "professional" version of the V6, the MDR-7506 is available - but it will cost you. Mine set me back about AUS $220 but they retail for about AUS $250.
I tried the MDR CD780, but only briefly and in a noisy store. The comfort was impressive, as was the one-sided, removable cord. Sound wise, meh - it was OK. It certainly did not wow me, I'm sorry I can't recall any more details about the sound.
If you do want the 7506 headphones, they can be purchased from a professional audio/video store in Fairfield, Melbourne:
www.soundcorp.com.au
The guys there were pretty cool, and they let me come in an audition the phones at great length, and in relative quiet! I seem to recall they were available in QLD and possibly SA and WA. Use the search funtion link at the bottom of my message
I should have asked this earlier, but what do you want to use the headphones with and for? Listening at home? From a portable? In a noisy environment? The 7506s excel in that they are extremely verstatile headphones. They can be effeciently powered by almost any source, including portables. They fold down, so they are relatively portable. Also, being closed in design, they attenuate outside sounds to an extent that they can be used on public transport and in libraries (they don't leak sound as much as an open-air headphone). Sound-wise, they are very upfront and lively. Some complain of harsh highs, but I don't find this. One criticism I do agree with is that the mids are slightly recessed, so they are not the warmest sounding headphones around. In terms of bass response though, the bass is deep, tight and controlled and IMPACTFUL! This was a very important feature for me. FInally, they offer really superb instrument separation which I guess if why they work so well as studio monitors.
Depending on your requirements, there are a few other cheaper options around for you to audition:
Earbuds: Sennheiser MX400 - AUS $30.00
Clip ons: Koss KSC-50 - AUS $ 50.00 (ish)
Open headphones: Grado SR-60 - AUS $180.00
I have all of these headphones, and not surprsingly, they all have their strengths and weaknesses. If you can cope with open headphones that clip on, I am sure you will find the Koss KSC-50s will work extremely well with the sort of music you listen to. For more detailed reviews of these phones, use the Head-Fi search function
http://www.head-fi.org/forums/search.php?s=
Good luck! (and DO try to audition the more expensive phones using music YOU are familar with).