I only really ever take this bait when I'm overworked and underslept, so I guess here we are.
Dude. This seems like a really backwards and lazy way to get this done. If you want to hire a designer, find some designers you like (if you're having a hard time finding designer portfolios, a good starting point would be to check out gigposters.com...it's got a whole bunch of them!) and then contact them to see if they're willing to work for whatever you're willing to offer, and within the timeframe that you need this thing to happen. That's pretty much the most basic, bare minimum way you can show designers that you actually value their work and also that you have any interest in how your project turns out. Do a little bit of legwork and you'll end up way more satisfied with your options than just putting out an open call for whoever feels like getting in touch.
Or don't do any of that stuff. I'm not your mom. Unless you wanna come over here and wash some screens and feed me Coke Zero and Twix, I don't really care what you do.