Seller Unresponsive after payment.

Hi,

I just bought a DAC https://www.audiogon.com/listings/lisb6ae1-space-tech-laboratory-da-512dsd-2-da-converters?show_listing=true from @madavid0 last Sept.14 and have paid through Paypal once I commited the buy option of the listing. He only responded once after one week of no communication and said item will be ship that week because he said he was out of town. I understood that and it is almost two weeks after and no replies on my messages.

How do I go about it? And what kind of feedback do I give for other potential buyers to be aware of what kind of a seller he is.