I'll agree with Heathfield - as long as you're a careful shopper!
My experience of shopping in Singapore is that you really need to shop around for the best prices. For example, if you see a T-shirt you like, here in the UK, it might cost a tenner in one shop but only �8 in the shop down the road. That's probably about the maximum price difference you might find. Singapore is very different!
You might see a T-shirt you like, in one shop, for a tenner. The shop next door will offer it for �1.50! However, that shop will want you to pay �60 for the trainers that you really like. Go back to the first shop and they're just �10!
Summary: Don't buy anything in Singapore until you've checked out the prices in several stores.
One more hint: Wherever you go, check your change (especially in your hotel). It's illegal to give or receive tips in Singapore but many employees seem to boost their income from the 'tips' which you didn't know you were giving. Drinks in the hotel bar can cost at least ten times as much as in a local bar. If the bar staff 'forget' to give you your change, it might cost you far more! (I went to the bar at a major hotel about ten times in one evening. The bar staff 'forgot' my change, until I reminded them about it, on every single occasion!).
Chris