I got my chair and my wife’s from an office furniture liquidator. They buy in bulk from companies that are going under or just upgrading. There will be some truly abused chairs in the lot, but most of the Herman millers and SteelCase hold up very well.
Look up used office furniture / office furniture liquidators, and get yourself a high quality chair for maybe $300-400 on the high end.
Second hand office chairs are great. Aerons were hard to come by during the pandemic but I ended up getting a stealcase leap for my wife, and a stealcase Amia for myself. The leap is better, but both are excellent chairs. I think they were $400 and $300 respectively