For doing it yourself I will once again recommend vinyl dyes as the top choice. It is easy to get a good end result with minimal effort as it requires no sanding, nothing more than starting with a clean case body. I did some mice with it and after almost 3 years it is now only starting to wear thin. Keep in mind I have contact with the mouse for many hours every day, much more than a typical person would with keyboard casebody so it should last even longer theoretically. The major con to them is they tend to have a pretty limited color selection.
Second choice with similar pro is Krylon Fusion, though it does not seem to be quite as resilient to wear. It has a much larger color selection though.
Third option is professional. Some body/chopper shop might be warm to the idea of doing such small pieces after hours for a reasonable price. But it all depends so you might need to make numerous calls to find one. Other similar option if you have any in your area might be some of airbrushing shops.
