Good question Grant. In fact we get asked this kind of question all the time, especially with these Chinese trading companies flooding the market with cheap carbon frames. But when comparing carbon frames these days there is little between them. Our frames are like any other open mold carbon frame except for a few things. Just like Tim has said in a little more detail:
First of is quality. We have a long relationship with the factory, and with that relationship comes benefits. We get the best quality frame that comes of their production line because we have been there personally and explicitly told them how we want our frames to be. Like mentioned above, we have our own "recipe" in the way the carbon is laid up to produce a higher quality bike. Ordering through any of the trading company sites will just get you a random pick from the line that may have quality issues.
Second is service. We stand behind all products with the Astuto brand on it, so if you were to have any trouble with the frame we would be there to fix it. When you buy off a trading site you are buying blind with very little guarantee that you will get any type of warranty service. We have helped some of our customers who have broken their frames in accidents and had them back on the road within days. Good luck trying to get that from a trading company. On another service issue, how do you know you are getting the right size frame? We have frames here in our shop with you can try out and see if it is the right size for you. From there we can make sure you get a frame that will fit you properly. That would be another blind buy.
Third is simple. The sites you linked above require a minimum order of 5 frames. Buying 5 frames where you know nothing about who is building it or what the intentions of the guy is on the other side are, is dangerous. Buying from us or like all LBS in that matter gets you the assurance that what you are buying is actually what you will get.
To sum up, there may not be much in terms of visible difference, but there is a large difference under the surface.
I hope this clears it up a little bit and if you have any more questions about our products, please feel free to ask.