Cashier's Checks:
Chashier's check/ postal orders can be sent and this is probably the best payment method. You have prove that the money was sent.
Cash:
Money sent directly in the mail is not the saftest way of sending money. I am not responable if it is lost or stolen in the mail. If this method is used you will probably want to wrap it in dark paper so one can not see threw the enevlope.