If anybody ever finds these for sale, I would be eternally grateful if you PM'd me a link. I will even give you a finder's fee.
Stuff like this, while not valuable in terms of actual cash value, is super rare. So I try to collect as much of it as I can.
Edit: Just now I was also able to track down the red one, Creepy Crawler. Looking for the two yellow ones now, in case you find them.