You can get HDB 2 bedroom apartments (renovated) from $1,800 per month depending on the area.
If you're happy to 'live like a local' and in Homelands areas you might be able to get cheaper.
I've found that for about SGD2,000 per month you can get a very nice, fully-furnished HDB apartment in the Toa Payoh area which has two MRTs and a little 'mini-town-centre' for all your daily needs etc ...
Of course if you've got money to burn you can spend up to 8,000 per month on a penthouse in a new building
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