That's beautiful work.
What sort of machine do you use? solid point, or hot wire?
This is a picture I did. Sadly the camera is rubbish, so it's lost a bit of detail and stuff.
http://www.tarotforum.net/attachment.php?attachmentid=8282
That was done with a hot wire machine. I can't get on with the solid point things. Although you can get some nice tips for stamping letters and that sort of thing. But they take too long to heat up.
I really can't say about your idea of a contest. I have never done anything like that. Though I know the raffles were popular.
I think it is a lovely idea, it's very generous of you to give your hard work as a prize, and your work is very beautiful, so a box would be a prize that anyone would be proud to win.
But how you would actually arrange it...
Well, I suppose that is up to you.
PS. It's great to talk to another pyrographer!
I have asked once or twice if anyone else on the forum does it, and no one has said yes. So perhaps all the pyrographers are keeping quiet, or possibly it is not a common craft amongst ATers.
Good luck!