Battery Storage for Household Solar

My neighbour and I have both installed rooftop solar this past year. Hers is a 5Kw system and mine is a 3Kw system. We are very disappointed by the feed-in tariff being paid to us (6.2c per KW), the high cost to get power from the grid (about 25c per Kw after GST/discounts)and our vulnerability to future price increases.
We are wanting some good advice about going off-grid with battery storage. What are the requirements, how much can we expect to pay for optimal set up and can you recommend a reliable/honest supplier (Melbourne western suburnbs)?