So, there are these cheap carbon frames on eBay that look like a real bargain.

http://cgi.ebay.com.au/New-STARS-Full-Carbon-MTB...

There are a few things online about them, most people that have taken the gamble seem to be happy. Of coruse the real worry would be having it snap in half while riding it but I cab't find any of those horror stories.
I was thinking of replacing the Kona frame I use on my comuter bike and this looks nice and light.