Hi, I'm possibly going to buy a 2nd hand Aeron as I've found one quite cheap local to me and was wondering what the latest was with your situation?
I sold it in the end! Managed to sell it for the same amount I paid for it fortunately (very quickly too). Opted for an IKEA Markus in the end and apart from the lack of adjustable armrests I'm very happy with it.
Absolutely loved the Aeron's back support but my butt pain never went away; I have a feeling it's probably due to me being too big for a size B (I'm a 6ft1 powerlifter build).
My advice would be if you can find it for a good price, give it a go. If I was able to sell it easily (I live in a small town in the South West) I imagine most could. If it works out for you then that's great, if it doesn't you'll be able to pass it on easily (as long as you don't soil it!).
I've started putting a saving pot towards something like an HM Embody / Steelcase Gesture in the mean time. If the Markus doesn't work out then maybe I'll stomach buying a 1k chair.
Hope my ramblings help.