Well, within the context of PGO being supplied with a pre-downloaded archive file (which it was), it is free.
You can login to Yahoo, get your groups list and load them all from archive files.
You can then read, sort & search them using PGO for the rest of eternity.
Its just the download function that's not free.
If you have a group with 10,000 members, only one person has to do the download.
Everyone else gets it for free.
That's 99.99% free

Cheers,
Wilson.