So I bought some wine & beer returning from the Philippines at DFS at Changi Airport.

Wine

DFS prices correspond to that on their Website http://www.dfs.com/en/airport-singapore/featured-brands/oyster-bay/oyster-bay-sauvignon-blanc-2011-2012-75cl-70000138048, that is 36.20SGD for 0.75L of Oyster Bay Sauvignon Blanc.

I checked the price with Cold Storage, which was 48.95SGD. So that's almost a 30% saving!

Beer

If you don't buy spirits, you can buy 2x3 cans of beer. 2x6.30SGD of the cheapest beer there, Carlsberg is 12.60SGD. A 6 pack of Carlsberg in Cold Storage is 16.70SGD, that's a 28% difference.

So how much is tax?

Hat tip: Thanks Valentine for explaining the duty to me.

In Singapore, duty on alcohol is $88.00 per litre of alcohol.

So for a 13% alcohol, 0.75L bottle of wine, it's $8.58. Goods & Services Tax is $3.20 per bottle. 48.95-8.58-3.20=37.17SGD. So ignoring tax, DFS is still a dollar cheaper than Cold Storage.

What about the UK?

Oyster Bay Sauvignon Blanc 75Cl at Tesco is 11.19GBP, which at best is 22.62SGD. That's with UK tax.

That's almost a 50% saving on Singapore duty free prices. Crazy.