Conditional shipping option?

[Ajeh]

Try this ...

Customize the file:
/includes/modules/shipping/fedexwebservices.php

with the code in RED:

        $methods = array();
// bof: check FedEx for > 40.00
        $_SESSION['usps_first_class'] = 0;
        foreach ($response->RateReplyDetails as $rateReply) {

              $methods[] = array('id' => str_replace('_', '', $rateReply->ServiceType),
                                 'title' => ucwords(strtolower(str_replace('_', ' ', $rateReply->ServiceType))) . $transitTime,
                                 'cost' => $cost + (strpos($this->types[$rateReply->ServiceType]['handling_fee'], '%') ? ($cost * (float)$this->types[$rateReply->ServiceType]['handling_fee'] / 100) : (float)$this->types[$rateReply->ServiceType]['handling_fee']));
$chk_cost = ($cost + (strpos($this->types[$rateReply->ServiceType]['handling_fee'], '%') ? ($cost * (float)$this->types[$rateReply->ServiceType]['handling_fee'] / 100) : (float)$this->types[$rateReply->ServiceType]['handling_fee']));
if ($_SESSION['usps_first_class'] == 0 || $chk_cost < $_SESSION['usps_first_class']) {
  $_SESSION['usps_first_class'] = $chk_cost;
}
//echo 'FedEx Cost Calc: ' . $chk_cost . ' $_SESSION[usps_first_class]: ' . $_SESSION['usps_first_class'] . '<br><br>';
// bof: check FedEx for > 40.00
            }
          }
        }
        $this->quotes['methods'] = $methods;

Then customize the file:
/includes/modules/shipping/usps.php

          if ($this->usps_countries == 'US' && MODULE_SHIPPING_USPS_FIRST_CLASS_FILTER_US == 'True' && preg_match('#First\-Class#i', $type) && $cnt_first > 1) continue;
// bof: check FedEx for > 40.00
//echo 'USPS FedEx $_SESSION[usps_first_class]: ' . $_SESSION['usps_first_class'] . ' $type: ' . $type . '<br>';
//echo 'USPS $type_rebuilt: ' . $type_rebuilt . '<br>';
if (preg_match('#(first-class)#i', $type_rebuilt) && $_SESSION['usps_first_class'] > 40) {
          $methods[] = array('id' => $type_rebuilt,
                             'title' => $title,
                             'cost' => $cost,
                            );
}
// eof: check FedEx for > 40.00
        } else {
//echo 'MISSING! USPS $type: ' . $type . (in_array($type, $this->typeCheckboxesSelected) ? ' YES' : ' NO') . ' $method: ' . $method . ' $usps_shipping_weight: ' . $usps_shipping_weight . ' $minweight: ' . $minweight . ' $maxweight: ' . $maxweight . '<br>';
        }
      }  // end for $i to $PackageSize

      if (sizeof($methods) == 0) return false;

Be sure that on the Modules ... Shipping ... that you set a Sort Order on FedEx such as 10 and on USPS a Sort Order of 20 so that FedEx runs before USPS for this to work ...