Drupal - Create product programmatically

A commerce product is an entity like any other, so...

$cp->field_my_field[LANGUAGE_NONE][0]['value'] = '22';

Just a tweak: the create method on the product controller already has some defaults so no need to add things like is_new or status.

  public function create(array $values = array()) {
    $values += array(
      'product_id' => NULL,
      'is_new' => TRUE,
      'sku' => '',
      'revision_id' => NULL,
      'title' => '',
      'uid' => '',
      'status' => 1,
      'created' => '',
      'changed' => '',
    );

    return parent::create($values);
  }

So I'd just do:

$cp = commerce_product_new('product');
$cp->uid = 1;
$cp->sku = $product[sku];
$cp->title = $product[name];
$cp->language = LANGUAGE_NONE;
$cp->commerce_price = array(LANGUAGE_NONE => array( 0 => array(
 'amount' => $product[sale_price] ? $product[sale_price] : $product[retail_price],
 'currency_code' => 'USD',
)));$product[retail_price];
$cp->my_field[LANGUAGE_NONE][0]['value'] = 22;
commerce_product_save($cp);