I would say that these days "professional" starts at MSRP $600 and "high quality" at $1000. This rules out anything you'll find at the nationwide B&M office supply chains, Best Buy, etc.
Keep watching CL. You WILL find the $600 chairs for $100-$200 and the $1000 ones for $300-$600. If you live in a smaller city use the CL of a larger one nearby (that's what I had to do).
If you can't wait: Look around for local companies that specialize in supplying businesses with used office furniture. The good quality stuff lasts forever, so this is a thing. It will be more expensive, but still cheaper than new.
Totally right....I finally was able to score a lightly used Aeron for $350. Since it was local, no shipping. I have an Aeron at work that I have used for 10 years and it is still just as good as when they bought for me.....so I had to have one for home. I know it's tough to pay out this kind of money, but when you figure the number of "less costly" chairs you will go through during the life of the more quality chairs, it makes the quality chairs look pretty competitive.