Recently signed up for Amazon Prime, and what decided me was learning that all seasons of this great show are now available via Amazon Instant Video. They are not available for purchasing, but you can watch them without commercial interruption. This alone has been worth the price of admission, as the saying goes.
Just watched the episode Hearts and Souls and while Amazon does not have the original-length episode, it is still one of the best of the series.
Have been kicking myself over the last few years for not saving my VHS tapes, since it did not occur to me that Seasons 5-12 would never come out on DVD. Thought these episodes were gone for good, and it is wonderful being able to see them again.