The cost of concrete varies dramatically depending on the region, dimension of slab, depth desired, and type being used. Without knowing any more information, it is difficult to give a complete answer. On average it is $41.75/m2.
One thing we know for sure would be that there would be turn-around time between order placement and the time the product is received in order to prepare for installation--typically 3-5 business days. For this reason, it's always best to allow at least 10% excess as a cushion - in other words if you need 20 square meters please add an extra 2 meters onto your actual needs so it gives you a buffer area once installation takes place. If you have any specific questions about what size or characteristic of concrete slab will