I'd also consider a CAAD from eBay or Craigslist. They are very nice and the people who buy them are always upgrading to carbon fiber.

It's the carbon fiber that makes those Chinese brands possible. They need a fridge full of prepreg, a little autoclave, and a mold. A factory or factories for making aluminum bikes has a lot more expensive and powerful equipment. The tubes need to be shaped and heat treated and robot welded. And so I don't think you will see a Chiner equivalent to a CAAD that is unbranded. There are certainly plenty of inexpensive aluminum frames that are not quite so high-end, though. Nashbar has a few, and Bike Island sometimes has unbranded frames that are the same as their Motobecane/Gravity/Mercier/whatever.

Like this one (FGSS) http://bikeisland.com/cgi-bin/BKTK_S...ls&ProdID=2858

or like this one (CX) BikeIsland.com - Bicycle Parts, Accessories and Clothing at Affordable Prices with Free Shipping