This will be good if you put it in a contest, many will be interested with this. Also the fund must be escrowed so people will not just be get into nothing afterwards. Many will show their interest if you put it on the campaign contest. And you can get more cheaper.
Yes, I agree, however you should be willing to pay premium price so that you can attract good designers. Believe me there are a lot of very talented designers here and paying good price will make them join in. But the only problem I'm seeing is that you will have a hard time picking the best. LOL. Goodluck to you. Also don't forget to escrow the funds as well.