Generally, auto supply stores like Pep Boys, Autozone, or Murray's, maybe even Wal-Mart (depending upon where you are in the country) should carry vinyl dye, though it's usually called "Vinyl Color".
The sort I've used is made by Plasti-Kote, and it comes in both a black (more gloss) and a matte black (closer to the look/texture used by most black plastic bezels)..it's opaque, and comes in a few other colors as well, including a semi-gloss aluminum color that goes very well with aluminum cases. I have heard of some other outfits that will mix custom colors, though I've heard those are more translucent, and don't have the same finish as the Plasti-Kote.
Used in several light coats, You would be hard pressed to find a difference between a true black plastic drive cover and a vinyl dyed drive cover..It won't cover up fine details like recessed details (compact disc logo, dvd logo, etc) nearly to the same extent as spray paint will, and doesn't have any special prep work that needs to be done to it, aside from the plastic being fairly clean--that can be done with simple water and a little bit of soap.
ranges around $5.00 USD per can, ought to last for several drive faces though.