I'd urge anyone buying a chair to actually go and sit on some at a store. What looks good in a catalogue might be absolute posture- and spine-wrecking hell on earth when it arrives and you finally park your ass and see what it's like.
When I bought my current chair I went to Staples and spent an hour (I kid you not) sitting on their display chairs for minutes at a time in my usual sitting positions to see what worked best for me.
Ended up choosing a £50 chair that looks unassuming, especially compared to the £LOL Aerons and what have you that they also had.
Given that I argue that your chair and desk are as important as your other HIDs when using a PC, and that class of device is more important than anything inside your PC's case by far, you owe it to yourself to try before you buy in this case.