I know colour contact lenses have been a big hit accessory in the past few years. I mean, even I was looking into getting a pair for myself to try. But honestly, as attractive as colour contact lenses can make you be, medically speaking, people should be aware of the risks you are taking on when purchasing from these online vendors or putting the lenses in your eye. These online vendors are really no different from street vendors that sell you pretty looking colour contacts. They will NOT be reliable for your consequent eye conditions or - in severe cases - blindness if anything happens to you.
I'm bringing this issue up because I work in an eye care clinic and I'm very shocked by the amount of teenagers that walk into the clinic asking me if I sell colour contacts and they want a pair without prescriptions. They just don't understand your eyes need to be fitted into a proper pair of contacts. Contacts come in different sizes and thickness, not everyone's eyes are the same size so obviously, not every contact lens will be the same size. It's not an one-size-fits-all shirt. Colour contact lenses are really no different from plain contact lenses. You STILL need to have an eye exam and a contact lens fitting so that the optometrist can find you a pair of contacts that sits comfortably in your eyes. A contact lens that's too small for your eye will cause irritation. Wearing your contacts for too long may cause dryness in the eye and always taking those eyedrops - in the long run - is NOT a good idea. Comparatively speaking, wearing a pair of contact lenses for over 8 hours is much like covering your breathing airways with a plastic wrap and not letting you breathe.
Anyways, now that you know a little more about contact lenses, it's better to ask your optometrist or just research a bit more about them before putting your money down.