I forget which service it is, but one of them gives you an estimate, ships the car to Texas for full inspection, then contacts you back and lets you know the change in estimate before cutting you a check. Problem is, the car is now in Texas so if you say no, im not sure they pay for it to be shipped back to you. Carmax would have been the easiest but the closest one for me is a ferry ride to CT + another 100 miles or so and then id have to figure out how to get home or have my wife follow me. Seemed like a huge hassle. Seeing as you should be a heck of a lot closer, it probably isn't a huge deal for you. Either way, all of those companies give you an estimate online with just a few clicks so you can both get an idea what you are looking at getting plus could use that as a baseline to a dealership.
There also is just putting an ad out on Facebook marketplace or craigslist. I know of a few guys that did that pretty successfully although you are prone tot he guy saying he will bring 12k cash then shows up with 10k trying to hope youre desperate and takes the low ball or whatever.