I have never heard of a Sky die-cast model. KappaSphere (www.kappasphere.com) offers a Solstice version, though, so that most likely means a Sky may be coming soon. Maybe you could e-mail them and ask. Also, try checking eBay.
We've been waiting for a while. I talked with the manufacturer of the Solstice model and they had no plans at the time. Said they would wait till the car was produced. Perhaps we need a call in campaign.
Do you really think it would be a good idea to get a toy version of the Sky before the real version? I can see it now...pulling out the model while visiting friends to go over all the cool aspects- in scale mind you. "...and this is the color we picked out. No, the trunk isn't very big, but if you look closely you can actually see the the tire inflation system unique to the Sky- it's right there in the corner of the trunk...see?"