You need to know that there are two types of color contacts- colour changing contacts, which work to change the color of your iris (and maybe a bit outside) or sclera.
Sclera are the full eye contacts that cover from tip to tip and look oh so cool on tv. They are only used very briefly though and many productions are replacing them with CGI because they are very tough for actors to wear.
They are also INCREDIBLY UNSAFE if you do NOT get them specifically sized for yourself. There are very few places that make safe sclera lenses (usually for the theatre) but because it is for your full eye, they really need to be fitted to you in person. Use of badly fitted sclera contacts, or prolonged sclera contacts usage, can cause PERMANENT eye damage. So if you are serious about these, you need to find somewhere reputable, close by, that you can get this done at. Preferably attached to a real optometrist.
Colour changing contacts, on the other hand, are much easier to find and use. I buy mine from Honeycolor.com but others have had success with pinkyparadise.com. Honeycolor allow for prescriptions as well. Red is common enough and you can get solid red coverage for your iris.
Some places also do mesh contacts. These are often used for zombies in white, but can come in red for a similar effect but colour change. (Essentially you get the colour over the pupil as well, which does mean your eyesight is obscured and you do need a handler when wearing the contacts).
If you have never used contact lenses before, you MUST go to an optometrist and get them to fit you for contact lenses and, importantly, teach you to safely put in and take out contact lenses.
PLEASE BE SAFE WITH YOUR EYEBALLS. They do not get better if you screw them up.
Sent from my iPad using Tapatalk