This CodeLet will redirect the user to checkout page when user clicks on 'Buy now' button on the product
Use the code and create a custom module
Make sure you keep the weight of the module high in "system" table
CodeLet
<?php/** * Implements hook_form_FORM_ID_alter(). */function MY_MODULE_form_commerce_cart_add_to_cart_form_alter(&$form, &$form_state, $form_id) { $form['submit']['#attributes']['value'] = t('Buy Now'); $form['#submit'][] = '_custom_redirect_checkout';}/** * add to card submit form handler * @param unknown $form * @param unknown $form_state */function _custom_redirect_checkout($form, &$form_state) { drupal_goto('checkout');}?>