Your idea about recreating the contacts list from the email messages stored on the PST files would work. For this you can use MailExporter to export the sender email addresses to an Excel file or to a CSV (Comma delimited) file.

Outlook can import the contacts from a CSV file:

http://support.microsoft.com/kb/295664

You can find further information about MailExporter exporting features here:

http://www.mailexporter.net/emailexport/

(Disclaimer, I am the author of MailExporter)

Your idea about recreating the contacts list from the email messages stored on the PST files would work. For this you can use MsgExtract to export the sender email addresses to an Excel file or to a CSV (Comma delimited) file.

Outlook can import the contacts from a CSV file:

http://support.microsoft.com/kb/295664

You can find further information about MsgExtract exporting features here:

http://www.maildev.com/msgextract/

(Disclaimer, I am the author of MsgExtract)