When I got my start in bargain books in the early 80s it was common practice among buyers, especially the bigger buyers, to always bargain with remainder wholesalers. The most common method of operation was to accept a certain number of titles at the asking price, and bargain for the rest. Some buyers would haggle for every single book. Now the only ones insisting on "a price" are the chains. Have you looked at a chain bargain section lately? How's that working for them?
Gradually, over the years, the smart buyers discovered that they would get nearly everything they accepted at asking price, and very little to none of what they bargained for. As the wholesalers expanded and developed their customer base, they found that the books most bargained for by the bigger buyers were the very titles they could almost be sure of selling out at their asking price if they waited a little for the orders to come in. This realization reversed the order in which lists were sent out and accounts were called on. In the early days, the largest accounts with the biggest budgets were called on first, as they would spend the most per visit. But as the wholesalers' cost per book increased, it became clear that the larger accounts were not a place to make profits. The big hagglers became the dumping ground for the books that could not be sold at asking price, or where the titles were on hand in such scary quantities that something had to be done to make them go away.
Now we live in a market where the biggest buyers, other than the chain buyers, never look at the price, beyond verifying that they are not silly high, and only focus on what they need for their customers. The smaller bargainers still meet with some success, but seldom receive a full order. I had one last week ask why they did not get the beautiful pop-up for which they offered $1 less than asking price. It all went to the folks paying the price, and some of them did not get any due to how fast it sold. I even had an account offer to pay more for a certain line as they were continually being beaten to the punch by their competition. This offer was turned down, as it should be.
I'm not saying there are not occasions where you should try making an offer. One example is if you have a local author, maybe not a big seller on the national market, whose title shows up on one of my lists in relatively big numbers. Chances are, if you make a reasonable offer, you can get the price down for a chunky quantity. But if you have been accustomed, over the years, to getting a discount or special net prices, you have become used to very low fill rates and generally low-sales titles coming through. Maybe it's time to recalibrate your buying strategy.