we as a community have no idea what the seller would do thus any answer we give is just conjecture
there is too much unknown .... which way is the book trending (up/down)?, how many others are available in that grade on the market at this time?, how long as the seller had the book up for sale and how motivated are they to move it immediately or are they fine holding out for a price they have in mind based on their financial needs or what they paid for it?, etc, etc, etc
seems like you at least have some good intel/data that you have initially gathered, so why don't you just message the seller with the info that you have gathered and see how they respond .... worse they can do is say no