As you know saffron is very expensive, but I have used it to make yellow rice and can't remember how much I used.
The less expensive alternative and just as good is to use powdered turmeric. I don't measure things, so just sprinkle it in the water with the uncooked rice ( til you are satisfied with the color) and cook the rice as usual. Turmeric is good for you, too.
You can put anything else in with the rice that you want.