I sat in one of these for around 4 years. Now that I work someplace with cheap, shitty chairs, I don't notice a difference. Definitely not worth it, IMO.
If you were able to get one for like $25-50, I'd do it. Otherwise, no thanks.
I'd look for alternatives over paying $1000 for an Aeron, but I'd gladly pay $400 for such a chair. [note: I do believe at least some sizes or versions of the Aeron are available at that price point - I haven't investigated heavily but a quick search suggests that is the case.]
I've had a couple different chairs at the $100-200 level, and they suck in the long run. They all bother my back with long-term use, and they also all fall apart. Do note that this is not related to my physical shape: I'm an average height, 160lb man, on the thin side. I USE my chairs, perhaps too much, yet that is the reason for this thread.
I received a Steelcase chair, not of the Aeron design or remotely similar, for free from a previous job. I love it. I would have paid a couple hundred for it, however, not in lieu of an Aeron.
I sat long-term in a Knoll chair model that was intended to compete with the Aeron, but it was not the same, and critically not received as a challenger to the Aeron thrown of comfort.
Perhaps some people, even with long-term use, can handle just about any chair. I am forever jealous of such adaptable human bodies. You must not feel much neck or back aches and pains throughout your daily life. I may be under 30 and never once approached out of shape or fat, but I've never had an upper body that refrained from constantly reminding me of its presence in the most awful ways.
For people like me, who are familiar with discomfort, I reckon cheap office chairs will only do more damage in the long-run, be it to the body or wallet.
Something that is of quality construction and fits the shape of the individual body is, for a lack of better phrase, worth its weight in gold. That said, different bodies have different shapes, which may be better served with different chair designs.