Hi Hon,
Our flat is about 92sqm? I guess you never opt for OCS.
If you have the floor plan just do the usual lenghtxwidth to get the sqm of the areas and minus from there. For now I just estimate minus away 20sqm? So you have about 70sqm to cover.
You mentioned, $70-$100 per sq meter
70sqm x 100 will be 7000 to buy those marble? I think when they state the price, they never include workmanship price. If you never opt for OCS, then you have to buy 5doors yourself which range from 200-500 per door in the market depending on the design and material. So I think you need to look around 8-10k.
Latest Price for Optional Component by HDB
4-Room
Internal doors*
$1,800
Flooring for living / dining room and bedrooms
$3,000
Total = $4,800