I have an Aeron at work and I love it. It's absolutely worth the cost over time. There's no 'wow' factor when you first sit, but you'll still feel comfortable in it after many hours, which is not the case with most chairs. I also have had some lower back issues recently and sitting in the chair actually makes me feel much better.

At home, I have a Steelcase Think plus lumbar support. I wanted something a bit less expensive and nicer looking for my bedroom. It's also great - I don't spend as many hours on it as I do on the Aeron and it's done a wonderful job so far - no back pain at all.

Before that, I used a $10 Ikea chair for two years, and I felt serious back pain after a few months. It's absolutely worth it to invest in a quality chair. Even though the price tag is depressing, make the purchase once. Your chair / back pain will become a solved problem for at least a decade.