Usually I buy things not available locally or sometimes they have certain sales together with shipping might still be cheaper.
ardneh: B&H provides UPS shipping, fast. Alternative you can try using the not that cheap and slow vpost. DDelectronic offers shop warranty, easier to seek help should things goes wrong. B&H you have to ship back etc....I am talking about if both are grey sets.
The limit should be SGD400 (inclusive the shipping fee).
Above that, you are entitled to contribute 7% GST to the government.