Hi Jadis,
As far as I know the S series are those that was produced before the advent of the LAB series. I believe only S9 and S10 were direct to discs. Some of those S series specially the first ones were pressed in limited quantities and just given to friends, associates and few sold. In the very beginning, it was a garage type operations and the mother of Sax was the one mailing out the LPs. All the S series had the Tower logo. As far a collectability for value ????? Cheers,