If someone sends the cash to you through Paypal, etc, then you should post the product as soon as possible, not 2 weeks later.
Communicate.
If you cant get to the post office, say so.
If you fail to contact the buyer after 2 weeks when you havent even sent it, expect a harsh message.
If this happens to me again, i will demand a refund, and you can send money back through Paypal.
Unbelieveable.