Where's the Rainbow Jetpack gone in Jetpack Joyride?

Where's the Rainbow Jetpack gone in Jetpack Joyride?

When I first started playing Jetpack Joyride I recalled the Rainbow
Jetpack, but at some point it seems to have disappeared from the store and
now I can't get the Hippy Achievement.
Any idea how to get it? I thought perhaps installing an older version
might still have it, but I don't have a copy in iTunes to roll back to.
Has it ever come up on sale in the store?
Dammit, I should have gone for the Hippy Achievement instead of Rainbow
Fruit when I had the choice between the Fruit and the Rainbow jetpacks.
FYI, the Jetpack Joyride wiki doesn't seem to give any more info either.