I've never tried any of these, nor can I really - I'm blind without my prescription so unless I wanted to still wear glasses they wouldn't work for me, but I still think they're cool.
Doing an Internet search for "black contacts" I see sites selling anywhere from $10 -$150, though I'm not sure the difference. But colored contacts are one of those little pieces with a huge impact that can really "make" a whole costume. For example, you could wear these ones to be either a Vampire as portrayed in the British Series "Being Human":
Of course, it helps significantly if you are as hot as Mitchell (and have a great accent)
Or you could very easily become one of the crazy residents of Bon Temps (True Blood) while under the Maenad's control:
(Though let's try to keep the orgies to a minimum, kay' thanks)
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