I've used spray dyes. They work very well, preserving the texture of the plastic.

But they're expensive. In my experience it takes three small cans to spray a medium-sized computer case evenly (like a Iici or maybe a compact Mac).

The dye is not totally impervious to damage - a very shallow scratch or scuff won't reveal the original color, but a medium or deep scratch will.

It is also possible to coat unevenly, if you hold the can too close. So you have to keep it at some distance - which unfortunately means more overspray, which means more of a mess, more smell, and more cans you have to buy.

So I would say it's worth it, if you're willing to go to a little expense and a good deal of mess and cleanup.