Try this:

		BoxCollider b = obj.GetComponent<BoxCollider>(); //retrieves the Box Collider of the GameObject called obj
		
		vertice1 = myobject.transform.TransformPoint(b.center + new Vector3(-b.size.x, -b.size.y, -b.size.z)*0.5f);
		vertice2 = myobject.transform.TransformPoint(b.center + new Vector3(b.size.x, -b.size.y, -b.size.z)*0.5f);
		vertice3 = myobject.transform.TransformPoint(b.center + new Vector3(b.size.x, -b.size.y, b.size.z)*0.5f);
		vertice4 = myobject.transform.TransformPoint(b.center + new Vector3(-b.size.x, -b.size.y, b.size.z)*0.5f);
		vertice5 = myobject.transform.TransformPoint(b.center + new Vector3(-b.size.x, b.size.y, -b.size.z)*0.5f);
		vertice6 = myobject.transform.TransformPoint(b.center + new Vector3(b.size.x, b.size.y, -b.size.z)*0.5f);
		vertice7 = myobject.transform.TransformPoint(b.center + new Vector3(b.size.x, b.size.y, b.size.z)*0.5f);
		vertice8 = myobject.transform.TransformPoint(b.center + new Vector3(-b.size.x, b.size.y, b.size.z)*0.5f);