Ford recommends changing the cam belt @ 150,000. I'd do that just to make sure nothing bad happens down the road. The price seems a little high, but used cars are all really expensive right now.
I'm hoping the car in question has a manual transmission. There are few reported problems with those cars.
I'd take the car for a very long test drive, city and highway, and listen for any odd noises and drive it pretty hard. With a car that old, it's hard to tell how well it's been maintained. Plastic and rubber pieces are likely to be a little brittle or worn out, especially the coolant tank. Check that all the electrical stuff works like it should. Chasing down electrical bugs can be frustrating.
If it seems to drive OK, take it to a mechanic and have them put it on a lift and check the underside. Ball joints, driveshafts, and all that. Look for loose links, bearings, etc. That can be expensive to replace.
Compared to most modern cars, Fiestas are pretty simple and easy to work on yourself. You can do basic maintenance in your garage.
Team O'Neil uses Fiestas for their rally school.
https://teamoneil.com/ They're good cars to learn on.
If it checks out, you're
probably OK. Change the oil and tranny fluid, and drive it. Fiestas handle well, and they get great mileage. Good little cars, overall.