A contractor wants to build a fill at his new construction site. He has two options for purchasing his borrow material. Site A has a soil with a unit weight of 2.5 kN/m3, a moisture content of 14% and a cost of $8 per cubic meter. Site B has a soil with a unit weight of 17.9 kN/m3, a moisture content of 25% and a cost of $6 per cubic meter. If the contractor needs a fill with a volume of 100,000 cubic meters and will place the material with a dry unit weight of 18.7 kN/m3, how much borrow material will he need to purchase? Which soil is the cheaper purchase for the site?