Thank you. I did edit the right file. after I changed as you indicated before, and the site won't show anything, I assume that there is something wrong with the code. I have no clue what I did wrong. I paste all the code after modification here. Please take a look and give me some hints.
<?php
/**
 * @package  HikaShop for Joomla!
 * @version  2.0.0
 * @author  hikashop.com
 * @copyright  (C) 2010-2012 HIKARI SOFTWARE. All rights reserved.
 * @license  GNU/GPLv3 http://www.gnu.org/licenses/gpl-3.0.html
 */
defined('_JEXEC') or die('Restricted access');
?><?php
$class ='';
if(!empty($this->row->prices)&& count($this->row->prices)>1){
  $class = ' hikashop_product_several_prices';
} ?>
  <span class="hikashop_product_price_full<?php echo $class; ?>">
  <?php
  if(empty($this->row->prices)){
    echo JText::_('FREE_PRICE');
  }else{
    $first=true;
    echo JText::_('PRICE_BEGINNING');
    $i=0;
    if($this->params->get('price_with_tax',3)==3){
      $config =& hikashop_config();
      $this->params->set('price_with_tax',$config->get('price_with_tax'));
    }
    $specialPrice = false;
foreach($this->row->prices as $price) {
  if($price->price_access != 'all') {
    $specialPrice = true;
    break;
  }
}
foreach($this->row->prices as $price) {
  if($first)$first=false;
  if($specialPrice && $price->price_access == 'all') {
    echo '<span class="hikashop_strike_price">;
  }
      else echo JText::_('PRICE_SEPARATOR');
      $start = JText::_('PRICE_BEGINNING_'.$i);
      if($start!='PRICE_BEGINNING_'.$i){
        echo $start;
      }
      if(isset($price->price_min_quantity) && empty($this->cart_product_price) && $price->price_min_quantity>1){
        echo '<span class="hikashop_product_price_with_min_qty hikashop_product_price_for_at_least_'.$price->price_min_quantity.'">';
      }
      $classes = array('hikashop_product_price hikashop_product_price_'.$i);
      if(!empty($this->row->discount)){
        $classes[]='hikashop_product_price_with_discount';
      }
      if(!empty($this->row->discount)){
        if($this->params->get('show_discount',3)==3){
          $config =& hikashop_config();
          $this->params->set('show_discount',$config->get('show_discount'));
        }
        if($this->params->get('show_discount')==1){
          echo '<span class="hikashop_product_discount">'.JText::_('PRICE_DISCOUNT_START');
          if(bccomp($this->row->discount->discount_flat_amount,0,5)!==0){
            echo $this->currencyHelper->format(-1*$this->row->discount->discount_flat_amount,$price->price_currency_id);
          }elseif(bccomp($this->row->discount->discount_percent_amount,0,5)!==0){
            echo -1*$this->row->discount->discount_percent_amount.'%';
          }
          echo JText::_('PRICE_DISCOUNT_END').'</span>';
        }elseif($this->params->get('show_discount')==2){
          echo '<span class="hikashop_product_price_before_discount">'.JText::_('PRICE_DISCOUNT_START');
          if($this->params->get('price_with_tax')){
            echo $this->currencyHelper->format($price->price_value_without_discount_with_tax,$price->price_currency_id);
          }
          if($this->params->get('price_with_tax')==2){
            echo JText::_('PRICE_BEFORE_TAX');
          }
          if($this->params->get('price_with_tax')==2||!$this->params->get('price_with_tax')){
            echo $this->currencyHelper->format($price->price_value_without_discount,$price->price_currency_id);
          }
          if($this->params->get('price_with_tax')==2){
            echo JText::_('PRICE_AFTER_TAX');
          }
          if($this->params->get('show_original_price','-1')=='-1'){
            $config =& hikashop_config();
            $this->params->set('show_original_price',$config->get('show_original_price'));
          }
          if($this->params->get('show_original_price') && !empty($price->price_orig_value_without_discount_with_tax)){
            echo JText::_('PRICE_BEFORE_ORIG');
            if($this->params->get('price_with_tax')){
              echo $this->currencyHelper->format($price->price_orig_value_without_discount_with_tax,$price->price_orig_currency_id);
            }
            if($this->params->get('price_with_tax')==2){
              echo JText::_('PRICE_BEFORE_TAX');
            }
            if($this->params->get('price_with_tax')==2||!$this->params->get('price_with_tax') && !empty($price->price_orig_value_without_discount)){
              echo $this->currencyHelper->format($price->price_orig_value_without_discount,$price->price_orig_currency_id);
            }
            if($this->params->get('price_with_tax')==2){
              echo JText::_('PRICE_AFTER_TAX');
            }
            echo JText::_('PRICE_AFTER_ORIG');
          }
          echo JText::_('PRICE_DISCOUNT_END').'</span>';
        }elseif($this->params->get('show_discount')==3){
        }
      }
      echo '<span class="'.implode(' ',$classes).'">';
      if($this->params->get('price_with_tax')){
        echo $this->currencyHelper->format($price->price_value_with_tax,$price->price_currency_id);
      }
      if($this->params->get('price_with_tax')==2){
        echo JText::_('PRICE_BEFORE_TAX');
      }
      if($this->params->get('price_with_tax')==2||!$this->params->get('price_with_tax')){
        echo $this->currencyHelper->format($price->price_value,$price->price_currency_id);
      }
      if($this->params->get('price_with_tax')==2){
        echo JText::_('PRICE_AFTER_TAX');
      }
      if($this->params->get('show_original_price','-1')=='-1'){
        $config =& hikashop_config();
        $this->params->set('show_original_price',$config->get('show_original_price'));
      }
      if($this->params->get('show_original_price') && !empty($price->price_orig_value)){
        echo JText::_('PRICE_BEFORE_ORIG');
        if($this->params->get('price_with_tax')){
          echo $this->currencyHelper->format($price->price_orig_value_with_tax,$price->price_orig_currency_id);
        }
        if($this->params->get('price_with_tax')==2){
          echo JText::_('PRICE_BEFORE_TAX');
        }
        if($this->params->get('price_with_tax')==2||!$this->params->get('price_with_tax')){
          echo $this->currencyHelper->format($price->price_orig_value,$price->price_orig_currency_id);
        }
        if($this->params->get('price_with_tax')==2){
          echo JText::_('PRICE_AFTER_TAX');
        }
        echo JText::_('PRICE_AFTER_ORIG');
      }
      echo '</span> ';
      if(isset($price->price_min_quantity) && empty($this->cart_product_price) && $this->params->get('per_unit',1)){
        if($price->price_min_quantity>1){
          echo JText::sprintf('PER_UNIT_AT_LEAST_X_BOUGHT',$price->price_min_quantity);
        }else{
          echo JText::_('PER_UNIT');
        }
      }
      if($this->params->get('show_price_weight')){
        if(!empty($this->element->product_id) && isset($this->row->product_weight) && bccomp($this->row->product_weight,0,3)){
          echo JText::_('PRICE_SEPARATOR').'<span class="hikashop_product_price_per_weight_unit">';
          if($this->params->get('price_with_tax')){
            $weight_price = $price->price_value_with_tax / $this->row->product_weight;
            echo $this->currencyHelper->format($weight_price,$price->price_currency_id).' / '.JText::_($this->row->product_weight_unit);
          }
          if($this->params->get('price_with_tax')==2){
            echo JText::_('PRICE_BEFORE_TAX');
          }
          if($this->params->get('price_with_tax')==2||!$this->params->get('price_with_tax')){
            $weight_price = $price->price_value / $this->row->product_weight;
            echo $this->currencyHelper->format($weight_price,$price->price_currency_id).' / '.JText::_($this->row->product_weight_unit);
          }
          if($this->params->get('price_with_tax')==2){
            echo JText::_('PRICE_AFTER_TAX');
          }
          echo '</span>';
        }
      }
      if(isset($price->price_min_quantity) && empty($this->cart_product_price) && $price->price_min_quantity>1){
        echo '</span>';
      }
      $end = JText::_('PRICE_ENDING_'.$i);
      if($end!='PRICE_ENDING_'.$i){
        echo $end;
      }
      if($specialPrice && $price->price_access == 'all') {
       echo '</span>';
      }
 
      $i++;
    }
    echo JText::_('PRICE_END');
  }
  ?></span>