I don't think any chair will give you great posture, (though the wrong one will definitely make things worse). You need actual exercise for that. In case you

I don't think any chair will give you great posture, (though the wrong one will definitely make things worse). You need actual exercise for that. In case you don't have $$$$ to spend on a high end chair, remember that the reason chairs cost a lot of money is partly so that they can be adjustable to fit almost any one. However, the right cheap chair that fits you also works fine. In other words, go into a store with lots and lots of chairs and sit on them. I found a $150 chair that works great for me, but will undoubtedly be wrong for somebody else. Also remember that the chair is only one part of the ergonomic equation.