Enable Custom option in bundle product

As a quick solution to add Custom Options to bundled products with dynamic prices you may try to tweak prepareProductSave method in app/code/core/Mage/Bundle/Model/Observer.php, namely just comment some code out as follows: 

/*
        if ($product->getPriceType() == '0' && !$product->getOptionsReadonly()) {
            $product->setCanSaveCustomOptions(true);
            if ($customOptions = $product->getProductOptions()) {
                foreach (array_keys($customOptions) as $key) {
                    $customOptions[$key]['is_delete'] = 1;
                }
                $product->setProductOptions($customOptions);
            }
        }
*/

To get rid of “Bundle with dynamic pricing cannot include custom defined options. Options will not be saved.” message you should hack app/design/adminhtml/default/default/template/catalog/product/edit/options.phtml template

//show error message
/*
if ($('price_type')) {
    if ($('price_type').value == '0' && $('dynamic-price-warrning')) {
        $('dynamic-price-warrning').show();
    }
}
*/