$4200 seem fair for The Addams Family (aka TAF) depending on the condition. I would check the following areas for wear and if any protection such as Cliffy's have been put in place to protector or prevent further wear. Here is the most common wear area found on TAF is the electric chair scoop because it is such a common and repeated shot along with the vault, the swamp and eject.
You can already see from the pic above there is some wear the Cliffy is not covering and you will probably come across this saying from seller's a lot when looking for a game "A Cliffy will or should cover that" :lol: I also forgot to mention check for wear around the rotating blue bookcase too!
Another common problem with TAF can be see on the very left in the last picture which is the center of the playfield where the magnets for "The Power" and you can wear caused from the past. I would also inspect the inserts in particular on the mansion and again referencing the same pictures you can see what some worn or bad inserts look like too. Check the ramp entrances for cracks as well as plastics too but keep in mind this is a 20+ year old game and has probably seen it's fair share of days being on routed and was very popular back in the day at the arcades.
The next thing I would look over briefly is in the head and check the area where the 3xAA batteries are located for any leaking or if it has been cleaned up recently. It is pretty easy to tell because of the green crud it leaves on the battery leads as well as damaging other near by chips/resistors around it and cause very random behavior. This is correctable and needs to be neutralized/cleaned properly because any traces left can still continue to grow or spread in the future. Most collectors typically change their batteries once a year on their birthday so they don't forget or else you can install a remote battery holder which is mounted off the board and on the side of the head.
Look at all the the board for burned connectors and other things which look suspect to hackery. Most of this is correctable and Menace (aka J.Santiago) is baffled at the efforts people with a hack when it was just as easy and sometimes cheaper to just do the repair properly. Hopefully you are local (GTA) and should you or anyone ever need board work repair or diagnostics remember Menace.
I hope I haven't scared you off but this is a big investment and sometimes if the game is a not up to par cosmetically, an electrical basket case or over priced it is just better to walk away. Being new to pins I would try to buy from another collector and do your reference checks by asking around or searching their past post history on here and other local pinball forums. Not every collector in this hobby is an honest one and some look for a quick flip or a newbie with cash in hand and antsy to buy their first game. Take your time and sure you will find the right machine for you. In the meantime, make a few friends and go play their games and perhaps they can even go check out potential games for you too. When in doubt come back here ask questions or post pictures for advice because it never hurts to get other people's opinion either. Good luck!