This is just an example of what you can do:

If you're trying to be economical, try some black shoe leather dye. You can get that from most stores. When it's dry, try black shoe polish on top of that or some auto trim polish.

 

Meguiars Back to Black is pretty economical, and isn't a dye that you have to worry about getting onto the paint. There's a cleaner and a protector, as well as a single-step one. I think the 2-step works a little better.

It worked pretty well on my ford plastics, I imagine similar results on Toyota plastic

 

Had that on my 2004. Paint is the cure as the original finish was pretty much sandblasted off. One of the phillips screwheads stripped when I was removing the grill to clean and paint so I canceled the job.