Contacts are not scary at all, and I say this as someone who has something even worse embedded in their eye: a piece of rusty metal that was partially drilled out and what's left is slowly scraping across the surface, leaving a massive scar in its wake, which necessitated glasses and contact lenses. See? Compared to that, a contact lens which is worn by millions of people every day without issues isn't so scary anymore.
First, Kama's advice and explanations are correct and honest. Very nice since when you're looking into something like this, sugar-coating is not what you need.
Second, Walmart USED TO be able to order red lenses, but can no longer do so as Ciba Vision has put a voluntary hold on their WildEyes line, so you'll have to look elsewhere. I've used contacts from Gothika before and have had no trouble with them, aside from the fact that they weren't prescription so I couldn't see.
Most importantly, since you say you've never cosplayed with contacts before, go to an optometrist! As Kama suggested, let them know why you want the lenses. They might think you crazy, but oh well. I had to fight with mine to convince him to order my Black Outs a few years ago. ANYWAY!
Make sure you get a contact lens exam (glasses exams don't cut it) and
a trial pair of lenses, even if they're plano. Make sure you don't leave there without knowing how to put them in and take them out without any problems or difficulty. Make sure you listen to them on proper care. And ask questions! Take horror stories you've heard with you! Bring them up and they can tell you how many are either exaggerated or avoidable. They can tell you what to look out for and what not to do.
Honestly, I've worn contacts since the fifth grade and I'm 31 now. I've never had problems with the lenses aside from an inside-out lens (easy fix), an accidental tear in the lens (makes your eyes itchy and sucks because you have to toss the lens), a case that leaked so the lens dried up, and occasional irritation that goes away with rewetting drops... unless it's allergies, then I have to remove them. Trust me, they're really not that bad so long as you can follow basic instruction.