Try the Rustoleum "Hammered" spray paint series. Dries to a real hard finish, but be sure you prime any plastic parts or the paint will stay sort of soft.
Any spray paint from one of the major brands (Krylon, Rustoleum, Dupli-Color, etc.) will do, just sand down the case and degrease before painting. Use a sandable primer on any plastic parts before spraying with your color coat and they should match well.
Willing to try something a little risky, try a medium to heavy coat of one of the "Hammered" paints and immediately overspray with a light coat of a "Metalic" paint. Amazing results if done correctly, sort of a spider web or marbled look, but really deep.