Sorry mate, but I'm with everyone else here. You're asking for someone to spend time designing something for you where you have little in the way of what you're looking for. You're asking someone to use their design skills and their own artistic influence to create something for you, free of charge?
The prop community works in kind. Nobody expects anything for free, not even a sketch. You could at least try bargaining. You say you do GFX, why don't you offer a trade?
(I'm also curious how you can do GFX if you can't draw your own sketch)
Maybe you should try DeviantArt and find a sketch artist taking free commissions, instead of a group of costumers.