Scammers

600 sgd would be the price for a maid's room- little room.
Did you actually see the room?

I've seen it just by pic.

it might not be a scam, go there personally if you have the time, i been to one that is $500 for a room in a 3-room HDB (government) apartment, just diagonally across Tiong Bahru Plaza. this is considered closed to city centre with a MRT station.

location much further away can be as low as $350 to $400 per individual room (non-sharing and not a maid/store room).

don't get your expectations high for low-priced apartments below $500. In 90% of the cases, those would not be individual rooms but rented on a shared basis. Definitely come here first to have a look before agreeing to anything, I've heard of persons having being conned into thinking those were individual rooms...

There are many rental scams in Singapore.
- Don't agree to rent without having visited the room
- Never send money before having the keys ("Western Union" equals to Scam!)
- Check whether the landlord actually owns the unit and is allowed to sublet (you can enquire at HDB or the Condo's management)
Even if you follow the above and everything else goes well, you run the risk of not getting the deposit back when you move out. That's very common!