I have one that came with my car - and I honestly didn't know that C-3's didn't come with them from the factory! Although I have at times pondered how much GM thinks they saved by not attaching it somehow - now I know "the rest of the story" HA!
I have one, too. Didn't for my first year of ownership, decided I would get it for Cruisefest. Glad I did. May not be a "must" have, but darn close. Greatly improves comfort level, and highly recommended. One of the best $40 you will spend, for any accessory.
I, too, am curious about the "Astro" tops. Please post a report on that. I am very interested. Especially since they "sort of" color match my car.
Hey Bud (Rare81)-like your Yoda with the Avalanche jersey. Go Avs!