Commands->Enable_Stealth(<VEHICLE_OBJECT_HERE>, 1);

int cost = 900;
int curMoney = Commands->Get_Money(obj);

if(curMoney >= cost)
{
    Commands->Give_Money(obj, -cost, 0);
}

INIClass *myINI = Get_INI("mydir\\myini.ini");

int cost = myINI->Get_Int("CATEGORY", //In the ini this looks like [CATEGORY]
                          "ENTRYNAME", //In the INI this looks like ENTRYNAME=1234
                          900); //Default value