maiborodava,
$oShop_Item = Core_Entity::factory('Shop_Item', 123);
$oProperty = Core_Entity::factory('Property', 123);
$aPropertyValues = $oProperty->getValues($oShop_Item->id);
if(isset($aPropertyValues[0]) && $aPropertyValues[0]->file)
{
$path = $oShop_Item->getItemHref() . $aPropertyValues[0]->file;
}