What to check before buying a 94 mazda miata?

The crank shaft pulley! While officially the 94 did not have a weakness here- mechanics some times still mess up when putting the key back in the crankshaft. It takes a flash light and an inspection mirror. With the engine running shine the light down on the pulley and see if it is running true. With the engine off use the light and mirror to check out the bolt in the center. Make sure it is flat against the pulley.
As about the rain rail, was it replaced when the top was done.
Use a magnet along the dog leg behind the doors. If there is any body cancer that was not fixed right, that is were you will find it.

taste the coolant if its sweet then its fresh if it tastes like raw cucumbers then its bad.

Pull out the dip stick and put the oil in between your finger and thumb to see if there are any gritter bits in the oil ,when you test drive the car put the car in a full left hand lock to see if the drive shave bearings are knocking and then do the same in a right hand lock.If you are not sure pay an auto company to do the checking for you ,it can save you a lot of money in the long run .

Always check the mileage, test drive it and make sure the transmission is good, i would check to make sure the heat and cold air works, and definitely make sure theres no hidden holes covered up by the floor mats!!

I tell you from experience that people do not generally replace a whole lot of new parts then turn around and sell the car that almost sounds more like someone exasperated beyond belief if you ask me. However if its in really good shape take it for an extended test drive. A 40 minute to one hour test ride minimum and make sure the car is in good shape. And please do yourself a favor take it to a mechanic for a hundred bucks a good mechanic can give you a pretty good heads up on the vehicle and its Cheap insurance for what you need a dependable Car. here is a link from nada guide I used a hundred thousand miles as a ball park idea to get a quite. so 3 grand is a good price if the car is Nice.

Damn near 20 years old!! Check Everything!!! Take it to a mechanic before any money changes hand or you will end up on Judge Judy.