radio button is really the only way to go, but with the radio button, you willl need to set the value to to either priority or overnight:
<input name="upgrade" type="radio" value="priority" id="priority" />
USPS Priority : +$2.00<br />
<input name="upgrade" type="radio" value="overnight" id="overnight" />
USPS Overnight : +$7.50
you will only need one set session behavior to set the upgrade session variable:
<?php
if (!session_id()) session_start();
if($_SERVER["REQUEST_METHOD"] == "POST") {
$_SESSION["upgrade"] = "".((isset($_POST["upgrade"]))?$_POST["upgrade"]:"") ."";
}
?>
the in the shipping rule for the priority, set the trigger to:
Session Variable 'upgrade' exists
AND
Based on session variable value:
if the session variable 'upgrade' has a value of 'priority'
flat rate of '2.00'
and in the shipping rule for overnight:
Session Variable 'upgrade' exists
AND
Based on session variable value:
if the session variable 'upgrade' has a value of 'overnight'
flat rate of '7.50'
