Recommendation for a Ergonomic Chair for Home-Office?

I am looking (Karan has been on the lookout also) for a good ergonomic chair for my study at home and want to get your feedback on which ones you like and what do you think the price is right for that? I also need to take into account shipping to UK if something is only available in the US (or buying in the US and shipping to UK given the £ to $ ratio).

What do I like? I have spent my last 6-7 years at work in a Aero Chair manufactured by Herman Miller and absolutely love them. There is also a newer version by them called Mirra Chairs which are supposed to be better.

Given that between I and my wife we are going to spend a lot of time in front of the computer, I don’t mind spending a little money on a good chair in the long run – cheaper to invest in the chair than in a chiropractorJ.

What do you recommend?