I sold to Carmax in 2018. Went to a Toyota Dealership at the end of rt. 37 and made preliminary arrangements to buy a truck. I had already got an offer for my trade-in from CarMax for $10.5k but wanted to see what the dealer would offer me since I was willing to trade. They offered me $7k and wouldn't budge and I declined. They brought the manager over and pressured me into taking the $7k and I told them I had an offer for $10.5k from CarMax and it made zero sense to take their deal. I told them that I would take $7k for my trade if they took $3.5k off their sale price to make up the difference. Why should I be the one to take a $3k hit for no reason? They declined and thought I was bluffing with the CarMax price and challenged me to go get the $10.5k. So I did. It had been a few months since my CarMax offer so when I went back they offered $10k which I gladly accepted. The salesman and the manager actually called me while I was at CarMax asking why it was taking so long. It had been ~1 hour, so not long at all. CarMax cut me the check right there and I went back to the dealership and signed the check over as a down payment. The look on their faces when I presented the check for $10k was was pretty cool. They were shocked and I heard them mumble something like "oh shit, we need to watch out for this...." or something like that. They are counting on people not doing their due diligence and accepting their shitty, lopsided offers. Get the CarMax or Carvana offers prior to talking to the dealer and have it presentable if the dealer lowballs.

I may have been able to get slightly more with a private sale but I just didn't want to deal with that hassle. Plus, when I was buying, trucks that I wanted (specifically having 3 child seat anchors in the back) were few and far between and I needed to act pretty quickly and didn't have time for the private sale. CarMax made it pretty easy, IMO, and I saved $3k versus selling to the dealer.