Build Your Own CD?

I know people have tried to build their own passive preamps, tube amps, and tube preamps, and that companies offer kits for these purposes. As I look at home theater and digital (CD components and players) I get the sick feeling that they are all the same on the inside and just packaged differently. There seems to be no reason you could not buy a phillips transport, Crystal D/A and the rest of the stuff necessary to put in the box to make a kick-ass cd player (a D/A would seem even easier), so who amoung us has thought of this? SACD components seem obtainable as well. The only problem is the interconnection and compatibility of the various of digital components, but if someone could tell us what to connect, I believe that it could be done. I am not saying that we could build something as good as Wadia or Sony SACD, but hey, could we build something better than most of the stuff out there?