I always wanted an Aeron. Finally got one and it's terrible. The bottom "breathable" fabric has to be so tight it's like sitting on a noncushioned chair. It might keep your ass cooler but at the expense of comfort.
I found a ~$150 chair on Amazon that is so much more comfortable and affordable.
Maybe it's because I'm a tall guy (and fairly overweight) but for me it's the mesh that makes it so good - it might feel tight and not exactly 'cushioned', but I can sit on it for hours without feeling sore, whereas nearly every other office chair after a while feels like I've sunk into the cushion and warped my sitting position - or hit the plastics/metal!