Unless you live in a major metropolitan area, chances are that your local print shop does not work with white ink.
But white on a color can be very eye-catching as a business card or on a flyer.
When a small shop like ours needs to have white text on something, we print a colored background, leaving the white paper to show through where the text is.
This, of course, requires that side of your document be printed in color. Generally color printing is much more expensive than just black.
If cost is a large factor (as it is for some small businesses), you might be able to get a similar effect with a grayscale image on colored paper. That would use only black printing and be much more cost effective.