Jeff's FKB Video Store has been updated, to include Season 4:

http://www.fatherknowsbest.us/Videosx.html

All together, over half of the 207 FKB episodes are now available on tape.

FYI:
The wayback machine at the internet archive http://www.archive.org/web/web.php has approx 330 of the http://www.fatherknowsbest.us/Videosx.html
webpages you can look up if there was anything there you needed to find.

I can't find anything but search engines on this website (and they are not coming up with anything). Can you help point me to the website where I could purchase episodes?