Possible fan art contest rewards (Patreon)

Hey guys, so I've been wanting to do another fan art contest similar to the one I did way back. I totally loved people's submissions!

But i was wondering what the ewards for participating (and winning) should be. I thought something on the lines of getting a $30 patron treatment for that month, but that wouldn't incentivize higer paying patrons too much.

So I'm asking you guys for ideas and suggestions. Write down what would make you interested in participating in a fan art contest for GGGB!