$re = '/€\D*(\d+)[^<]*/';
$str = '<span class="price" id="old-price-3">€ 200,00 </span>
<span class="price" id="product-price-3">€ 80,00</span>';
$subst = "$1";
$result = preg_replace($re, $subst, $str);
echo "The result of the substitution is ".$result;
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php