During my visit last week I was shocked to find cheap duty free liquor at the arrival hall of the Colombo airport. I bought vodka 1 lit for US $16 and napolean whiskey for $16. On the way out Blacklabel was on special 3 bottles for US $72 ( all 1 lit).
I found it much cheaper than the Melbourne,Singapore,KL in Malaysia or HK int airport duty free.
I did not look at any perfumes etc hence unable to tell the prices
I have not looked at the Dubai duty free shops though to compare the prices.