Hey so I have a great vintage chair for sale, you're interested?
Yes I am, but the asking price is a bit higher than I can afford right now.  Can you accept $25?
No, so that's clearly undercutting me. The chair is a rocking chair and has been in our family for ages. Are you picking this up?
Yes, I can pick it up.  I also have a 2-year old LaZBoy chair that I need to get rid of because it is too big for the room.  How about if you bring me the chair and take the recliner.  I'll pay you $25 for that.  Deal?
No, we have too much furniture, that's the problem. The lowest I could go is $40 and even that's pushing it.
How about $40, but you give me another piece of small furniture to make it worth it.  And I will pick up the furniture from you. Deal?