WordPress AJAX return 0 – My case

You function name and your ajax action callback name should be same.

add_action('wp_ajax_pdfAction','pdfAction_callback');
add_action('wp_ajax_nopriv_pdfAction','pdfAction_callback');

function pdfAction_callback(){
    $post = $_POST['pdfAction'];
    echo "something";

    wp_die();

}

Please update your php code with the above.

Currently, your php function is not getting executed.

Update:

The Ajax Script,

$(document).on('click', "#generate-pdf", function(){

    var price1 = $("#price1").val();
    var price2 = $("#price2").val();

    $.ajax({
        url: ajax_object.ajax_url, // AJAX handler
        data: {
            'action': 'pdfAction',
            'price_1': price1,
            'price_2': price2
        },
        type: 'POST',
        success: function(data) {

            console.log(data);
            console.log(data.price_1) // to access individual values

        },
        error: function(errorThrown){
            console.log(errorThrown);
        }
    });
    return false;

});

Register Ajax Action Url and Script,

function ajax_enqueue_scripts() {

    // Enqueue your javascript file 
    wp_register_script( 'ajax-scripts', get_template_directory_uri() . '/js/ajax-scripts.js', array('jquery'), '1.0.0', true );

    // in JavaScript, object properties are accessed as ajax_object.ajax_url
    wp_localize_script( 'ajax-scripts', 'ajax_object', array( 
        'ajax_url' => admin_url( 'admin-ajax.php' ), // admin ajax url 
    ));

    wp_enqueue_script('ajax-scripts');

}

add_action( 'wp_enqueue_scripts', 'ajax_enqueue_scripts' );

Ajax Request Callback function,

add_action('wp_ajax_pdfAction','pdfAction_callback');
add_action('wp_ajax_nopriv_pdfAction','pdfAction_callback');

function pdfAction_callback(){

    // Getting data sent from Ajax request

    $price_1 = $_POST['price_1'];
    $price_2 = $_POST['price_2'];


    // Prepare Data to be send back to AJAX request
    $return = array(
        'price_1'  => $price_1,
        'price_2'  => $price_2
    );

    wp_send_json($return); // Send JSON response back to our AJAX Request and die().

    // we don't require wp_die(); here wp_send_json() will take care of it.

}

You also should consider using nonce here for security purpose.