Just a little more info on titanium sprockets.
Shimano Dura-Ace ten speed cassettes have 4 Ti sprockets, the four largest sizes vary depending on the cassette. They cost ~$150 (for 11-23) to ~$170 (12-27). This is cost prohibitive very quickly.
Also the 7075 Al sprockets are hard-coat anodized (class III) for durability while the Ti is nickle coated for the same reason.
However you may be able to get Ti, and definitely Al bike chainrings on sale from some of these places. Think prelightened sprockets. Just don't bogart the Dura-Ace on me
Also any one who builds a robot with Campy should win the form over function competition immeadiatly.
You can get these from any number of bike cataloges:
www.worldcycling.com
www.coloradocyclist.com
www.supergo.com
www.nashbar.com
www.performancebike.com