In my experience the buyers who lowball will, when you counter, turn up with no more cash than their lowball offer.
Had this with a car. Guy wanted to pay 800 for a 1200 car, I said 950 minimum. He turns up, had a look, says he’ll take it at 800. Then protested he had driven 75 miles when I told him to do one. Should have driven 75 miles with 150 quid more in your pocket then mate. Numpty.
Now I just won’t deal with people whose first and only question is ‘what’s the lowest you will take’. Same as people whose entire message is just “£xx?”. No, got better things to do with my life than deal with chancers like you.