If you have any kind of actual pain from your current typing setup, this is the only answer that makes sense. Forget the marketing surrounding expensive chairs - there isn't really as much science as they claim.
If you don't have any pain from sitting/typing and are just looking to buy a "good" chair, I would suggest
(a) spending money instead on a sit stand desk that allows you to change posture during the day (changing posture frequently is more important than sitting in one ideal posture for long periods).
(b) if you can spend money, get a chair that was some adjustable knobs - height, tension in the back, lock to stop rotation and removable arms maybe. Try local second hand office furniture shops and try out different options. If you buy a second hand chair you don't like, you can usually sell it again without a big loss and keep looking for better options.
If you don't have any pain from sitting/typing and are just looking to buy a "good" chair, I would suggest
(a) spending money instead on a sit stand desk that allows you to change posture during the day (changing posture frequently is more important than sitting in one ideal posture for long periods).
(b) if you can spend money, get a chair that was some adjustable knobs - height, tension in the back, lock to stop rotation and removable arms maybe. Try local second hand office furniture shops and try out different options. If you buy a second hand chair you don't like, you can usually sell it again without a big loss and keep looking for better options.