I'm going to have to go with everyone else on this one. I just recently purchased red eye contact lenses as well. However, I went through an optomitrist for them. Even though I do not require prescription lenses, I still went in for an eye exam and whatnot. You need to be sure your eyes are able to use contacts since some people can't wear them. Take my advice, and the advice of the others, take the safe route and go through a credited optomitrist. The cost of the contacts through them is less than buying a cheap pair online, and wrecking your eyesight permanently. You only have one set of eyes so take care of them.
"Imagination is the Preview of Life's Coming Attractions"
~ Albert Einstein