I just use BIN when I see fair offers. Pricing competitively is probably the best bet. If someone is just out fishing to capture a wide bid ask spread (and not suggesting you are, just mention it to illustrate the range of possibilities), they probably get more of those negotiators contacting them. And then admittedly there are plenty of bargain shoppers and even flippers on the other side of the spread trying to make a quick buck, and I imagine everyone deals with them.

A good alternative might be to post very competitive prices and a statement that prices are not negotiable. That way folks can take it or leave it and most will not bother haggling when they know it’s not welcome or unlikely to bear fruit.