Вот вариант рабочей сортировки по цене
if ('section' == $this->GetPageName())
{
CModule::IncludeModule('catalog');
$dbRes = CCatalogGroup::GetList(
array(), array('NAME' => $arParams['PRICE_CODE'][0])
);
if ($arRes = $dbRes->Fetch())
$arResult['_PRICE_ID'] = $arRes['ID'];
}
$arAvailableSort = array(
"name" => Array("name", "asc"),
"price" => Array('catalog_PRICE_'.$arResult['_PRICE_ID'], "asc"),
"date" => Array('PROPERTY_NEWPRODUCT', "desc"),
);