Use this:
<?php echo $this->getLayout()->createBlock('catalog/product_price')
->setTemplate('catalog/product/customprice.phtml')
->setProduct($_product)
->setDisplayMinimalPrice(true)
->setIdSuffix($idSuffix='amit')
->toHtml(); ?>
Instead of <?php echo $this->getPriceHtml($_product, true) ?>
Thank you!