Where do I send application for china visa in madrid? visa price and who should the cheque made to?

What is your purpose to China? for tourism for business? If you can not go to the embassy in person, you can entrust others to do it on your behalf. Anyway, you can refer to http://es.china-embassy.org/esp/lqyw/asuntosconsulares1/ first for more details if the Chinese embassy in Madrid accept mail application.