They are working on re-introducing them to the solstice/sky public!
There are other options as well:
The Cobalt SS brembo calipers work with the Solstice/Sky- but you cannot retain your stock wheels without a spacer.
The Boxster (Non-S model) calipers will work as well, but you'll need to make your own bracket- if you need dimesions- hit me up.
Both of these upgrades are less than 600.00
If you're a big spender, contact TCE for about 1200~1500 you can upgrade your rotors, calipers, lines and all that.