I've forwarded the transcripts of the emails, along with his full name, city & state, along with my concerns to:

Santa Barbara County Sheriff (shipping address is Santa Maria located in Santa Barbara County)
FBI Internet Crime Complaint Center
eBay Trust and Safety Department
Cox Cable - his Internet Service Provider

It appears that at least one of these contacted him fairly quickly as I received another email from him. It was far more concise than earlier emails and contained far less swearing (although it did contain a few choice words).

Thanks to everyone for their concern. I really do appreciate it.

Hopefully we can get back to having fun with room keys.

Jim