If you are a single working stiff, with no income other than Salary, it's so easy you can do it yourself. Get yourself a copy of Pub 54, You can download a soft copy here:
Paying attention to Wages (1040), dividend & Interest (Schedule B), and 2555-EZ (Income Earned abroad exclusion). These should possibly be the only ones you need. It can obviously get a lot more complicated, but these are easy and not really complicated at all.
Or you can go here:
http://singapore.usembassy.gov/tax_prep ... apore.html
I have been doing my own tax returns since 1969 both at home and here since 1983.
I do not vouch for any of the sites listed in the Embassy page as I've never used them, but be prepared probably for a bill over US$500 at least (just guessing).
25 years ago there used to be an H & R Block here but no more.