You are dreaming and you can't buy a good CF frame for $399 now. You can but a frame with fiberglass lugs wrapped in carbon for 399 now.

The bike industry uses less than 5% of global carbon fiber production. The demand is increasing in other sectors.

Carbon pricing already dropped for 2011 model bikes. I doubt it will drop much further. Even if it did a 50% cost is materials would not result in a 30% drop in the price of the finished product.

Chinese labour costs are rising.

Transportation costs are rising.

Oil prices have risen and will stay there.

In short, not going to happen.