Anywhere between $5000 and $20000 per month. Depends on your expectation. Safe to say, it also depends on where you are from. An Aussie couple would have different expectations than an Indian couple.
IT is not well paid in singapore unless you are in a very niche field. For 5 years experience in common technologies you can expect maybe $4500 - $5000. If you have a rare skillset then the premium for that skill will be exponentially proportional to the number of people who have the same skillset.
Some figures from the singapore department of statistics
Average monthly household income in Singapore in 2010 was approx $7200, while the median household income was $5000.
Median monthly household income for those staying in private apartments, condos and private houses (ie. excluding those staying in subsidized govt housing) is approx $12900
PP, where did you get that statistics about income for those staying in private ppties? I have never heard of this being calculated... is it provided by the government?
Sounds quite low to me... ?