Once you agree to something it's a contract - no longer negotiable. Either buying or selling - if the guy wants to bargain AFTER it's been agreed on, the deal's OFF - no matter what! Even at the original price the ad said - I won't deal with them.
I get a kick out of the yo yo's that call on an ad - "would you take xxx?" (sale) But they haven't even seen it!
I tell them obviously they want to negogiate, so I go UP the difference they suggested.
They say that's the wrong way -
"Not for me!"
There are enough ligitimate buyers and sellers that you don't have to bother with idiots.
And no, I won't take it half way across town or across the state - "to meet them 1/2 way" - if they want to see it - they have to come here! They always play the game after you met them somewhere that it's not what you said it was - and expect you to drop the price further.
"Gomer - Not for sale to you at any price now!"
And - I got a fist-full of counterfeit bills one time - and a couple of "closed accounts" checks. Now we meet at a bank, - we go to the window together - the teller counts out the cash from her drawer to him while I watch, then he hands it to me. If it's any significant amount of money, he'll understand. If they object - it may have been a scam anyway - no loss to you.
A friend advertised a Ramcharger - $2000? - he got over $15,000 worth of counterfeit "certified" checks - some just photocopies, some very bad print jobs on a computer printer, mailed to him. The police wanted them. How can people be so stupid?
It must work sometimes, otherwise there wouldn't be so many scammers around.