1. All Ergonomic chairs are good for everyone. Wrong, all chairs do not suit everyones height, structure and personal requirements.
2. Ergonomic chairs are expensive. Wrong, well made chairs with adjustability do not nessessarily need to be expensive, a $1000 chair may not have any more eronomics than a $300 chair.
3. Ergonomic chairs are only for people with injuries. Wrong, ergonomic chairs are designed to stop injury as well as help with injuries.
4. All new chairs are ergonomic. Wrong, without testing a chair you cannot know if it suits your needs.
5. Ergonomic chairs are only for people sitting on them all day. Wrong, whether you are doing 10mins or 10 hours keyboard work, your chair needs to support your particular body and needs.
Conclusion
If you are after a good quality ergonomic chair, go to your local office furniture shop and test drive the chairs, if they are not helpful, move on and find a retailer that cares for your needs, and knows what chair will help with your particular requirements.