You have a mistake on dealing with a newbie always read the sticky thread before you deal.

Do you know how to use the escrow? Always check this list of escrow here if you deal to lower rank members.

If you deal to lower rank member you should always use an escrow to avoid scam attempts like the scammer you linked above.

What I noticed from the scammer trust list he receives bad feedbacks but he receives trusted feedback from a trusted forum member here. You maybe need to contact him and bring him here to start conversation why he is still not sending the payment yet.

Edit: Looks like he's here.