This is the absolute cheapest I have seen these. They range from about $560 - $999 in Australian retail stores
One word of advice I hear from many - When charging remove the back piece slightly out of the helmet to reduce strain which breaks the solder on the weak charging port
Great price compared to local sellers, but these have gone for under $350 in the past. According to camelx3, $325 is best price. But AUD is noticeably weaker than before.
As for the product itself, significantly slimmer than other offerings. Reduces wind noise from having a bulge out the side.