You can find deals on the Aeron - after the dot com bust up they became sort of like soviet nukes - they went everywhere and became very accessible 
Kidding aside, I picked mine up on craigslist last year. It was only a year old, highly adjustable model with the tuxedo pellicle. List was $900, I paid $450. The guy had just bought a Knoll "Life" chair (I guess he was a chair aficionado) and his wife wanted this Aeron gone. It worked out well for me! I sit in a not so wonderful chair at work all day (albeit expensive in its own right) and then the Aeron at night at home. Its not even a comparison.
Kidding aside, I picked mine up on craigslist last year. It was only a year old, highly adjustable model with the tuxedo pellicle. List was $900, I paid $450. The guy had just bought a Knoll "Life" chair (I guess he was a chair aficionado) and his wife wanted this Aeron gone. It worked out well for me! I sit in a not so wonderful chair at work all day (albeit expensive in its own right) and then the Aeron at night at home. Its not even a comparison.