The Herman Miller Aeron is probably the most famous desk chair ever designed, so if the chair you're currently sitting on in your home office isn't going to cut it for the long haul, we highly recommend the upgrade.
The Aeron doesn't come cheap, but Madison Seating has a stash of open-box Aerons that you can get for $389 right now through the company's eBay storefront, or even less if you buy more than one. The chair is configured with optional extras like adjustable lumbar support and fully adjustable arms, and includes free shipping, free returns, and even a 10 year warranty from Madison Seating.
For context, the same chair new as configured from Herman Miller would cost well over $1,000, even with the company's current 15% furniture discount.
Open Box Herman Miller Aeron Chair | $389