In general, Amazon doesn't ship electronics to Singapore. To bypass this, one has to use vPost. vPost has their own shipping charges for different types of items. Camera is one of them.
If one is looking at camera with prices close to SGD1000. It's probably not worth it. Note that there's compulsory 7% GST to be paid at the custom.
Also, as mentioned by others, there's the warranty issue because it's not local coverage.
However, if there's a friend in US, it might be more worthwhile.
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For books, Amazon ships books cheaper than any bookshops in Singapore, INCLUSIVE of shipping charges. In most cases.