Wait for the Singapore Apple Store at Knightsbridge to be opened by early 2017.
You will only need to pay about $200 to have your Macbook Air battery replaced at the Apple Store
I paid S$200 at the Hong Kong Apple Store to have my 2011 Macbook Air 11" battery replaced as you will need to pay around S$500 to have it replaced at the "authorised apple service centres" in Singapore as they have to cover their overhead cost such as rental and labour.
Wait for Singapore Apple Store to be opened and send your macbook air to have it repaired there. Half the price