Good luck !
As long as nothing major needs done, that $5200 sounds fair. See if he has records of the timing belt service. If no records, I would certainly talk him down a bit on the price.
Also, check the wheels for excessive peeling chrome. If there is any chrome peeling up at the tire/wheel bead sealing surface area then you'll likely be plagued with air leaks. Usually bead sealant works well but I've had it fail on me a couple of times so far. Maybe take a tire gauge with you to check the air pressure in each tire real quick. Obviously, a low tire will tip you off that something there isn't right.
These wheels are hard to get in good condition. Stock size aftermarket wheels are few and far between.
Things that tend to rust out first would be the license plate lights. In the rust-belt area, those light sockets and their bracket go first and they are not easy to fix properly compared to a lot of other vehicles. Next to go tends to be the front bumper, under the plastic cladding.
None of these things would stop me from buying this vehicle, especially if you talk him down to $4500!!! It's nice to know this stuff first so you can budget for the repairs later.