code: public function getPerUnitAmount()
      {
          $amount = $this->getProduct()->getPrice();
  
          foreach ($this->getOptions() as $cartOption) {
              $amount = bcadd($amount, $cartOption->getOption()->getPrice(), 2);
          }
  
          foreach ($this->getExtras() as $cartExtra) {
              $amount = bcadd($amount, $cartExtra->getExtra()->getPrice(), 2);
          }
  
          return floatval($amount);
      }
docs: The calculated item total. This includes the
  options & extras, but excludes quantity.
  
  @return float