I noticed someone had mentioned the Amazon Kids sale, but I thought this needed an additional thread. A lot of the Hanna-Barbera sets have been reduced to $13.49 and are not part of that sales link. I haven't been able to find a one stop link for these titles, but thought these were some nifty bargains.

Here's the sets I saw:

Adventures of Aquaman: The Complete Series
Birdman and the Galaxy Trio: The Complete Series
Dastardly & Muttley in Their Flying Machines: The Complete Series
Hong Kong Phooey: The Complete Series
Josie and the Pussycats: The Complete Series
Perils of Penelope Pitstop: The Complete Series ($13.99)
Space Ghost and Dino Boy: The Complete Series
Tex Avery's Droopy
Tom & Jerry Spotlight Collection Vol. 1
Tom & Jerry Spotlight Collection Vol. 2
Tom & Jerry Spotlight Collection Vol. 3
Yogi Bear Show: The Complete Series ($14.99)

There might be more.

I just bought this for $18 as part of the sale you mentioned. Stupid Amazon and their defunct price guarantee policy! Probably not worth my time to send it back and re-order.

It appears the titles you mentioned, OP, along with many others are part of a huge sale covered in this thread.

I want some of those hanna barbera sets but I hate double sided discs