All that's missing is one cheap enough for large numbers of people to have one sitting in the garage.
You can build your own CNC mill, per instructions available online (Instructables has quite a few, and I'm still looking at DIYLILCNC.org (DIY Lil' CNC - build your own for $700, using free plans) with covetous eyes. Slowly getting my workshop plans in place, though, and I'll probably start in on the "heavy" shop machinery via Lindsay Books' 'Build Your Own Metalworking Shop From Scrap' series by Dave Gingery. A CNC mill is well down the list for wants/needs.
3D printers are a little pricier than that, but you can get kits for smallish ones like the Makerbot (courtesy of Make Magazine) for something like $1400, that can print something in the neighborhood of a 6" cube. Stuff that can print using sintered metal like Brad mentioned will be... more expensive. But it's coming - just 6-7 years ago, something like the Makerbot would have been several thousand dollars, instead of in the neighborhood of $1500, and would not have been as capable.