Jeff,
I don't know if you ever got access to anti-phishing's phish archive;
but if you didn't, you might put up a donation link on your site and
solicit contributions that would specifically go toward paying for
access to their database, for at least 1 year. Of course, if their
database isn't updated as quickly as yours or isn't helpful for the
first year, then you obviously wouldn't continue it...
Just an idea...
Matthew Wilson