Plugin idea?

I have a plugin idea, it is a trading one. I can't really find a good trading plugin that allows a player to make a sign practically saying what they want and what there will to give up for it.
Line 1: [Trade]
Line 2: T: 32 WOOD_LOG
Line 3: W: 32 BIRCH_LOG
But you will need a chest for your stuff and the other players stuff that you wanted.

Thanks if anyone can link me to a plugin to this or even create one! If you create one (for free) you can become Dev on my server! Thanks