The battery and supporting hardware is available to order...

The battery and supporting hardware is available to order through tesla's website

https://www.tesla.com/en_AU/powerwall

Battery itself is $8000
Hardware is an additional $1050
Our installation cost was $1600
but ours was a fairly straightforward instal
tesla's range is $1150 to $2900

there is a waiting list, not sure of how long it is

Depends on your electricity price, FIT and whether you use
most of your daytime solar already, but 6kw of
panels and 5kw inverter sounds perfect for the
PW2.

If you have the dollars sitting in the bank earning
very little, it is probably worthwhile, if you have
a mortgage, it could be better option to pay that down,
but depends on how much value you place on
being independent to the grid I suppose

cheers grant