public function UnitPrice()
{
if ($this->Order()->IsCart()) {
$buyable = $this->Buyable();
$unitprice = $buyable ? $buyable->sellingPrice() : $this->UnitPrice;
$this->extend('updateUnitPrice', $unitprice);
return $this->UnitPrice = $unitprice;
}
return $this->UnitPrice;
}