Since you're rating is negative (and I don't care why) half payment should be done upfront (or what the designer requests) this way there is some trust involved.
I'm not entering, but might as well monitor the contest as if somebody design something but didn't won and if like it, I might as well buy it. also, OP, you might want to ask MOD to change the title of your thread. So that people will come and enter as the prize changed ($125)