Hi netteoh,
There are few printers available in Singapore. Usually the
minimum lot size is 1,000 pcs to start with.
If your budget does not allow you to do that, you can 'share'
the printing costs by informing the printer, and they will wait for
right quantity to commence printing. The costs varies, depending on
whether the printer has the master copy, the book needs editing
etc
Get a quotation before you start.
You can personally distribute the books or the printer can
distribute as well.