The Woz signature was screen printed onto the case.
This is one of the more complete Woz LE sets I've seen, but I'd still only value it maybe $100-150 over a similar condition/similarly equipped standard IIgs.
There are no red flags to me here. This is a genuine "Woz edition" IIgs-it's just that, like a lot of limited editions, it's not really that "limited."
From what I've read around here, these aren't THAT rare and 50,000 (?) were made.
I'd guess they all shipped with the documentation, but most probably threw the certificate away.
The certificate was a mail in registering return.
Certainly over priced IMHO