Can Apple help if the trade-in estimate changed due to the vendor changing valuation between quote and exchange?

After the release of the new MacBook I checked the trade-in value of my old one. It seemed reasonable, so I ordered the new MacBook to replace it. After trying it out I decided to make the trade-in but discovered that the value of my old MacBook had decreased. I couldn't make it to the store for a few days but when I did the trade-in value had decreased yet again. I told the employee that this seemed unfair — I made the original purchase based on the trade-in value offered, which gave no indication that it was subject to change and, in fact, their trade-in page says that the estimate offered is valid for two weeks after the receipt of the new device. (I also had to type in the serial number of my laptop, so I figured they could easily verify the original offer.) He seemed irritated and got the manager, and the less said about my customer service experience the better. In the end I was told that there was basically nothing that could be done and that they wouldn't honor the original amount. I have no idea how they set the price, but cynically it seems to me like once I made the purchase they — knowing from my serial number that I checked the value a few times — lowered the amount repeatedly over the course of a few weeks. I felt pressured to trade-in for fear of the value falling even lower (one fourth drop since the beginning of the month) Is there a way to dispute or address this monetary negotiation or a process to advocate for me getting a higher payout?