If you would like to use a mediator, we certainly can.... but here are my thoughts.
Firstly, no they don't give back scammed FG. They just lock the scammers FG and give him a Scammer tag. No FG is returned.
Your JSP account is less than a week old, and you have NO trading history. I've been on this site for 7 years. (Not trying to stretch my e-peen here, just saying I have much more trade history here.)
Here is my most recent trade:
http://forums.d2jsp.org/topic.php?t=71312345&f=228&o=108/25/2014 6:55:00 AM Sent -13,000.00 (25,104.33 -> 12,104.33) to Mythix (1,430.00 -> 14,430.00) WoW Gold
He sent first.
I have donated real money to this site(donators are indicated by stars next to names), have Donor Forum access, and trade regularly. I have a lot more to lose than you do.
So you can trade first, or if you think I'm going to risk losing my remaining 7k FG after I trade you, we can use a mediator which will take much longer. It's up to you.
/edit: As far as your comments about proof goes... yes, you can take screenshots or record the trade as you see fit.
We will discuss the trade via PM, where we will give each other our in game names and decide on where to meet. We will make the trade clear.
You: [AMOUNT] Mesos for [AMOUNT] FG
Me: Correct, I accept this trade.
Then you have proof that this was the agreed upon amount and that there was no confusion. Take screenshots of your inventory before and after the trade. You have proof you sent me mesos.
If you're still overly concerned about this, we can do the trades in smaller increments at a time. Or, again, get a med.
This post was edited by Shiner on Aug 25 2014 02:33pm