found this one - and it is aust stock with 2 year cr kennedy warranty (not a grey import, despite most of their stock being grey). free delivery at the moment too (need to pick standard delivery to see the discount, not express which is the default).
next lowest price i found was $469 delivered from dwi ebay (but grey). dcw sell it for $549. teds have it for $629 (although their rep would go as low as $520).
this is the new sigma lens released a few months ago. competition would be the tamron 18-270 lens - which is slightly more expensive (cheapest i found is $490, grey import).
obviously superzooms have their flaws, but apparently a decent all-in-one lens.
EDIT - nikon & canon mounts available.
Nice focal length! but if your like me you will have a massive collection of lenses =p
50mm 1.8
40mm 2.8
70 - 300mm
150 - 500mm
24 - 105mm
18 - 55mm < Never use it! =p
think that's about it! I shoot with two camera bodies to avoid having to change lenses all the time.. but looking at the lenses you have listed it is a pretty good travelling lens!
Review on this lens found here http://www.dpreview.com/lensreviews/sigma_18-250_3p5-6p3_os_…