Your right I don't have that kind of cash, I can spend about 2K on a book, and I am sure this would be a good price for the buyer, then again he/she could say no. I have been collecting these Whitman's for awhile and trying to complete the set.
I feel for you Bloomis as I know what it's like to need that one book to complete a set. I had a similar 'buy or leave' conundrum with the ASM 184 All Detergent. Unfortunately, when certain books take on near mythical status, and that catches on, anyone who finds one puts an eye watering price tag on it. You can't really blame them, as it's likely a collector with deep pockets will bite rather than wait. I waited, and that patience was rewarded in the end. Only you know what you're prepared to pay. If you're uncomfortable, leave it. Make an offer which you think is reasonable. You never know.