Have a conversation with them about the loudspeakers and their system. When they come to pick them up let a friend know and arrange to contact them after the sale. The buyer with $4k in cash has more to worry about being scammed then you do.
Selling towers - keep getting bad actors/scammers when doing local pickup only.
I have been trying to sell my tower speakers on US Audio mart. I don't have the patience to package them up and mess with freight shipping. So, I advertise them as local pickup only and I set the price pretty cheap. But, the 2 serious buyers I have gotten seemed to be bad actors/scammers. I would catch details that lead me to cancel the arrangements before they happened.
I guess it's a bad idea to do local pickup only when selling audio equipment?