I want to apologize to you for humanity. I don't envy your position. It's why I just pay what's asked for seeing as how you have to deal with this. The first show I went to in, I dunno, 38 years, i was looking thru an xmen box and a guy kinda nudged me aside and I thought, "I guess that's how things are now" and kinda let him share my space. He got a bunch of books, haggled with dealer slammed them down, obviously not getting his way, screaming "The customer is always right!" and stormed off still screaming, "THE CUSTOMER IS ALWAYS RIGHT!" I was so embarrased I kinda wanted to just leave.
EDIT: I buy not to flip. True, I will sell my collection in 20 years and do hope to sell for more than I bought, bout most importantly it's books I care for, not what's hot or maybe I'm the sucker every dealer hopes for. I tend to stay with a small group of sellers that I feel is fair, fully understanding I have no idea what fair is. I usually don't do my homework. I got 500$, I want that book, it's priced at 500$, here you go.