Don't forget about GST here. Gov here aren't so friendly about oversea purchasing though. It will be different if u go there for holiday then buy it, better still, can claim back VAT at airport...Voila!
Yes, be aware that you'll be charged 7% GST upon receiving the item in S'pore.
Also, credit/debit cards normally charge a slight mark up on the exchange rate. So if Yahoo says SG$1.4:US$1, treat it as SG$1.43:US$1. Calculate prudently.