The Avengers: Season 5 (1968) (HD Digital) - $5 on Amazon and FandangoNow
Probably in tribute to Diana Rigg passing away last week. She was only in 2 seasons (as Emma Peel) - Seasons 4 & 5.
Regularly $9.99. It's 25 episodes. In color. I rewatched them earlier this year, and although quite cheesy (esp. Season 5), Diana Rigg was such a classic beauty. I only watched the series for her. https://www.youtube.com/watch?v=idtYckLIZnI