If upgradeability is your thing, and that Macbook Air has you down, why not take a break and put together your very own Apple ][+ with nothing more than some LEGO. You could add anything you wanted to your new Mac then, right down to Lightsabers.
Chiu-Kueng Tsang has put together a nice little recreation of the famous computer, right on down to its innards. Pretty nifty. I’ll take two. Hit up his Flickr page for more pictures.