Here's my 2˘ on this.
I've been meaning for months to create images for these cards. Mocking up a card is fast. Like, 10 minutes to get a nice card. It's finding art that takes forever. As we've been talking about. So.
I personally am willing to use whatever art on fan cards. I know that there are some (like eHalcyon) that strongly prefer to only use free-use art. That is admirable and I respect him for it. I'm not personally willing to do it. I tried with Tithe. Bleh.
I messaged eHalcyon a while ago requesting that he find some art for these cards. My logic was that he's the person I know that cares most about the art not being in the public domain, so he must have some experience finding such art, etc. He messaged me back, but I then didn't get back to him for months. Because I'm a jerk like that.
Ideally I would like to say, "Yes, only free use art will do!" But that would make me a huge hypocrite, because I just use the best looking art I can find for my own cards and I'm probably not going to change them anytime soon. So if you can find good free use art, great. If not, so it goes. I'm not going to mandate it.
Aaaaaanyhow, Showdown. If you want to mock up these cards and make them into printable sheets, I say go for it. I was going to do it myself, but if I'm realistic, it would be better to delegate. I'll create a thread for cataloging the winning cards and if you send me images/sheets, I will add them to that thread. If people want to link/post art suggestions in that same, thread, great!