The Plox portable phone batteries are on sale with a 20% discount to the public.
The 3000 series for the iPhone 4/s is discounted to US$40 + 20% off which is a bargain $32 with free delivery worldwide (Usually US$50).
The 6000 series for all smart phones except iPhone - US$60 (20% discount) + Free Delivery (Usually US$75)
Yeah these do seem over priced.
One thing I do like about these… attached USB cord!!! but yeah a lil exy. I got a 9000mAh double delivered - Amazon to US-Forwarder and then to Australia for less actually.
Just a PSA, 6000mah externalbattery/powerbanks do not equate to 3x of a 2000mah Phone charge.
There are conversion losses. Google will gladly provide you with the technical details.
In a nutshell, battery has a different voltage compared to the charging current output voltage. Generally really really super high quality external batteries may only have 10% loss but majority of these external batteries have an average of 25% loss.
To put this in terms, the 6000mah external battery only have an effective capacity of 4500mah.
It's important to note that the Plox 3000 series is MFi approved (that means approved by Apple as completely compliant). This means that you are completely covered when it comes to using the device to power your apple gear.
On top of this, the Plox device has all built in cabling so you don't need to carry a cord with you. There are a few others in the global market, but not many. That's what you are paying extra for.
you probably should indicate the 3000 series is a 3000 mAh battery backup and the 6000 is a 6000mAh battery.
and I'll mention you can can get larger capacity batteries for alot less elsse where e.g 6600 mAh for $30 from this deal -
http://www.ozbargain.com.au/node/113880