There are essentially three types of colored contact lenses. Depending on what you want yellow contacts for, you should find the exact type you want, and then within that type, the different manufacturer’s styles will differ.
The first kind will be tint, solely for visibility. They are usually light green or blue tints, and they just help you find your contacts when you drop them. These aren’t really considered colored contacts, but more as regular contacts that have tint because once you put them on, you will not see the tint anywhere.
You won’t find yellow contacts with this style because yellow is already easy enough to see. These visibility type contacts are just for clear contacts typically.
The second kind of colored contact will be enhancements. They are not designed to totally change the color of your eyes but more just to add a slight tint. They do affect your eye color, but only slightly. These are more often found year-round and not just for costume or Halloween purposes.
They can be used by people with light eyes or dark eyes, although the ones with lighter eyes will always work better.
Colored tints are the third kind, and the more common for yellow colored contacts for your eyes. These will completely change the color of your eyes, usually regardless of what your natural color is. If you have dark eyes these work great because they cover the regular color of your eye completely.
These will be used more often for costume or Halloween partises. You can find them in a lot of different styles and designs ranging from vampires, wolves and zombies. There are also silly designs like flowers or smiley faces.