The domain registration is set to "private" so a check with "whois.com" returns no good info other that the domain itself is good till 2022.
I think all you can know is what HPL said.. When you put something in the cart a msg at top says the cart is not setup for payments. So they have a working website, a working cart, but the cart has not been configured. I'm not familiar with this site. Have they sold before using same cart? If so, then they decided to abandon the cart without removing the cart scripts, or, they have some other problem with the cart host. All you can do is try the email form once a week or so. But I'd have to wonder... if the cart is not configured have they configured the contact form with their proper email? (rhetorical)