Appreciate your comments. Anything in particular I shall watch out for ?
I was thinking of doing this transaction in public place in everyone's view, what else can I do make sure I am not robbed or scammed.
Bring someone with you. Meet up at a very public place. Avoid offers to do the deal in a hotel room (even if they insist) or inside a car, especially if they intend to drive somewhere "to get the coins" or "to do the deal in a private location".
A good place would be a bank. If the seller is legit, they will want assurance that your $40k is genuine money. Suggesting a bank is therefore good for both parties. You get to transact safely inside a bank (can't get any safer) and they get to check your money, perhaps by depositing it into their account. Be careful of requests to first get your money and check if it's ok. For example, by depositing it into their account first to see if the bank accepts it and is therefore genuine. Once deposited, they can just walk out of the bank and ignore you.
It's a sensitive element of the transaction, the who-goes-first part. Either you pay them first and when they are happy, they send the coins or they send the coins first to your wallet and if you're happy, you pay them.
Selling in person can be a tricky and risky business. Try to get to know the buyer a bit more before meeting up. Like where he lives, a phone number perhaps, facebook and maybe even googling him.
And lastly, when coins are sent, be sure (and doublecheck!) that they were sent with the correct mining fees. This is very important. If the fees are extremely low, there is a chance the transaction will never confirm and it will return to the sender's wallet. Check for other things like doublespending or if the transaction has previous unconfirmed inputs with very low mining fees.
