Bought the Apple Watch Magnetic Charging Cable when I was in UK for holiday. It cost £25 (S$53) excluding tax refund. I can’t really remember how much the tax refund was, but it is probably the same price in Singapore after deducting the tax refund.
In case you are not aware, the charging cable that comes with Apple Watch Sports is made of plastic whereas for this cable, it is metallic. This is the same charging cable that comes with Apple Watch.
Length wise, the default Apple Watch packaging comes with the 2m charging cable which is a little too long for my liking. I find 1m in length is just nice.