3 submit buttons to modify ubecart veiws

Hi,

I'm new with the internal drupal code, and i try to modify ubercart catalog using hooks, but i can´t find the answer. i try to create first a form with all the components and later i will try to modify ubercart, but is impossible for me because i have not experience about that.

My project:

I have one ubecart catalog with:

5 Regions with a price by region
3 Users with a price by user
3 Duration with a price by 1year or 1 month

Them when the client select all this 3 options i have to show the sum prices + 3 format options:

EX: 1 user + 2 regions + 1 month => PDF FORMAT= total ; EXCEL FORMAT= total, WORD FORMAT= total

And them the client hay to push add to cart to pay his selection

----my code until now----

--php
// $Id$

/**
* Implements hook_menu().
*/
function input_menu() {
$items['input/online-store'] = array(
'title' => 'FocusEconomics Consensus Forecasts',
'description' => 'FocusEconomics Consensus Forecasts',
'page callback' => 'drupal_get_form',
'page arguments' => array('eshop_form'),
'access callback' => TRUE,
'weight' => 1,
);
return $items;
}

/**
* A longer form with more elements and attributes.
*/
print '

';
function eshop_form($form, &$form_submit) {

//Form Regions
$form['regions'] = array(
'#type' => 'checkboxes',
'#options' => drupal_map_assoc(array('mayor_economies'=>t('Major Economies'), 'euro_area'=>t('Euro Area'), 'nordic_economies'=>t('Nordic Economies'), 'asia_pacific'=>t('Asia|Pacific'), 'eastern_europe' =>t('Eastern Europe'), 'latin_america' =>t('Latin America'))),
'#title' => t('Regions'),
'#required' => TRUE,

);

//Form Users
$form['users'] = array(
'#type' => 'checkboxes',
'#options' => drupal_map_assoc(array('1user'=>t('1 User'), '2-5users'=>t('2-5 Users'), '6-10users'=>t('6-10 Users'))),
'#title' => t('Users'),
'#required' => TRUE,

);

// Form Duration

$form['duration'] = array(
'#title' => t('Duration'),
'#type' => 'radios',
'#options' => array('1month' => t('1 Month'), '1year' => t('1 Year')),
'#required' => TRUE,
);

$form['more_selection'] = array(
'#type' => 'markup',
'#markup' => '' . t('For more users suscription, please contact us', array('!url' => url('contact'))) . '.',
);

//Submit buttons

$form['pdf_only'] = array(
'#type' => 'submit',
'#value' => t('Buy Now'),
'#prefix' => "",
'#suffix' => "",

);

$form['pdf_and_excel'] = array(
'#type' => 'submit',
'#value' => t('Buy Now'),
'#prefix' => "",
'#suffix' => "",
);

$form['excel_only'] = array(
'#type' => 'submit',
'#value' => t('Buy Now'),
'#prefix' => "",
'#suffix' => "",
);
return $form;
}
print '

';

/**
* Submit function for input_simple_form().
*/
function eshop_form_submit($form, &$form_state) {

// Display a message upon successful submission.
drupal_set_message(t("I like @regions, too!", array('@regions' => $form_state['values']['regions'])));
}