I think this deal has been around for a long time (I bought this last year at this price, the price haven't changed since then).
That being said, it's still one of the cheaper option available (cheaper than best price on staticICE, $39.00). There is one eBay seller who's selling cheaper than Amazon AUD $25.49 who doesn't meet the Ozbargain eBay post guideline (Also, I am slightly hesitant on recommending them because I've heard about fake KSC-75s as well).
Anyways, this headphone frequently appears on recommendations when someone asks for a budget headphone out under $100. I personally think there is some hype on this headphone, but at this price, it's hard to find something that sounds as decent as this one. Other than how uncomfortable it is to use it (the clip requires frequent adjustments until you get it to the position you like), I think it at the very least, worth its price.
You can use it to replace the units of PortaPro (they are interchangable). It's slightly uncomfortable without the headphone band, so many people choose to get a headphone band that KSC-75 units can mount onto i.e. PortaPro headphone band etc.
EDIT: Forgot to mention this, but apparently the headphone pad can get damaged very easily (I've never changed mine, but so I've heard), I'd recommend buying spare pads along with it as well (though if you want to get it from Amazon, you'd need to spend over USD $25).
Using the Amazon Currency Converter
Items: AUD 18.75
Shipping & handling: AUD 7.47
Total before tax: AUD 26.22
Estimated tax to be collected: AUD 0.00
Order total: AUD 26.22
http://www.headphone.com/collections/best-headphones-under-1…
http://www.innerfidelity.com/content/innerfidelitys-wall-fam…
Just in case someone wants to know why I said it frequently appears on budget headphone recommendations.