I have an astro black car, I want it to be black black, not purpleish/blueish/black. What would be more affordable paint or vinyl? And what would look better.

 

If you aren't willing to spend $5,000- $10,000+ for a new paint job, don't even bother repainting the whole car. Vinyl will be much cheaper, but it won't be the same..as your door jambs, engine bay, inside the hatch areas, etc..will still be Astro Black. Good paint jobs are expensive because there is a lot of labor to remove parts, prep them, paint, reassemble, and properly finish.