You need a model with GPS and cellphone link, obviously.
While it might be convenient to mount a cheap used iPad permanently in the cockpit, you’d miss the many benefits of its portability.
Bet your iPad gets lots of use outside the aeroplane as well, so why not the best you can afford. A good new one is cheap as chips compared to regularly updating a laptop.
I haven’t used a computer in many years- everything gets done on my iPhone or iPad, including secretarial work for two organisations, lots of research, correspondence, thousands of pix and videos, watching movies and listening to music.
until