As almost ten persons worked on this project totally for free I don't really think it's respectful to only pay one person. However I'm conscious that it'll be difficult to find a talented graphist capable of imitating another's one art for free. So that's why I don't really have an answer to that question at the moment.
Are you capable of doing work like the exemple I gave on my other post ? If yes, please let me see some of them so we can see if you're able to help us after an
agreement in the future.
Also, good look for your own project, gamedev is a domain so intesting where everyone as a lot to learn !