You have just stated that this is required for the darknet market, why not find someone at that same darknet market to act as escrow?
I doubt anybody here is willing to put their hands in the first for a few extra bucks. That being said, if the transaction is legal, you might find a suitable escrow in the services section of the marketplace here.
Because on Darkmarket 95% guys are scam... I need some legit, so this BTC-asia.com u think is not legit?
but thank you.