I buy a lot of old books that aren't that easy to find anymore. In such situations in the past, I have managed to buy the book by contacting the seller directly

I buy a lot of old books that aren't that easy to find anymore. In such situations in the past, I have managed to buy the book by contacting the seller directly and telling them I'll buy it right away for some percentage of the price (50-80%). It has worked a few times.