Alienware and Acer Predator should be one of the more well known
on in sg
They will cost around 3k and above for a water cooled system and
with high end graphics card.
I think custom built one will cheaper, there is this gigabyte 3D
mecury casing that comes pre installed with pump, radiator etc.
Cost around $300+ to $400 if i remember correctly.
Add on:
I have emailed alienware before about getting them in Singapore.
This is their reply quoted from my email:
Anyway, this email was sent back to me in 2007, and maybe some
of the information might have changed.