Drupal 7: form api options from specific entity (node_type)

gistfile1.php

<?php
  $entity_type = 'node';
  $bundle_name = 'gift';
  $fields = field_info_instances($entity_type, $bundle_name);
  $options = array();
  foreach ($fields as $name => $field) {
    $options[$name] = $field['label'];
  }
  $form['field_price'] = array(
    '#type' => 'select', 
    '#title' => t('Price'),
    '#options' => $options,
    '#default_value' => variable_get('field_price', ''),
  );
?>