$basket = $newOrder->getBasket();
$item = self::getExistsItem($basket, 'catalog', $product['offer']['externalId']);
$item->setField('CUSTOM_PRICE', 'Y');
$item->setField('PRICE', $itemCost);
$item->setField('DISCOUNT_NAME', '');
$item->setField('DISCOUNT_VALUE', '');
$basket->save();