I understand that there exist some huge email repositories, where one
can obtain copies of emails that have previously flitted around the
Internet.

I need copies of email sent in connection with a transaction in or
about February of 1999, and other emails commenting on that
transaction and/or related matters.

The principals all say they no longer have the computers from which
the email was sent, and hence that the email is no longer available.

Is there some other way [e.g., the supposed email repositories] to
resurrect pertinent email?

If you can direct me to such repositories, etc., then you will earn
the price for this question.  If you actually come up with some of the
email, that would be even more valuable.