Probably the most reputable online store in the US. I've bought 4 lenses from them.
how much are they selling this lens, any additional charge to look out for .
how about warranty. Is it cover in Singapore?
Lets see USD600 x 1.41 (est exchange rate) * 1.085 = SGD918 (is assumes that shipping is free from US to SG), 1 year international warranty.
You can buy a local set in singapore for around 930-950 cash 2 years warranty.
I rather buy in Singapore.