The Aeron is overrated anyway. I bought one and hated it. Gave it away.
I currently have a Steelcase Leap which I got for "cheap" on craigslist. It works well.
A good office chair is kind of like a mattress -- you spend a lot of time in it, you should buy something decent. To further justify the cost -- most of the big brands (Herman Miller/Steelcase/etc) have great warranties.
I had an issue with my chair (back tensioner messed up) and Steelcase sent a dude to my house to fix it. $0.
You can gamble on some random nonsense from Staples or Office Depot, but odds are it'll start falling apart after about a year of use.