Hi,
HikaShop already has microdata which supports prices with their currency. You can simply enable the microdata plugin via the Joomla plugins manager for that.
So you shouldn't have to do that.
If nevertheless you want to do it with custom code, you should do differently and instead of separating the price and the currency, you should add such tag in the views where the prices are added:
<?php $currency_id = hikashop_getCurrency();
$null = null;
$currencyClass = hikashop_get('class.currency');
$currencies = $currencyClass->getCurrencies($currency_id,$null);
$data=$currencies[$currency_id]; ?>
<meta itemprop="priceCurrency" content="'.$data->currency_code.'" />