At home I still use the L-shaped Steelcase desk I picked up used at an office moving sale literally DECADES ago. It still has the company property sticker on it from the original owner; the sticker is on there REALLY good and I didn't feel like futzing with it and potentially damaging the edge of the desk. IIRC I only paid like $10 or $20 for it, but you had to disassemble and haul it out of the recently vacated office building yourself. It still looks and feels pretty much exactly the way it did when I originally acquired it some ~30 years ago -- i.e. a somewhat used, but built-like-a-frikkin-tank piece of industrial furniture.
I used to have another similar one (minus the L section) that I acquired for free. Back in the '90s a couple of former co-workers and I started a small consulting business. When we moved in to our new office space the landlord informed us that the tenant across the hall had skipped out on their lease and disappeared a couple of months prior; we were told we could help ourselves to any furniture we wanted from the suite across the hall (presumably because every piece of furniture we took was one less piece they had to haul away). I ditched that desk the last time we moved since I really didn't have a use for it. I also grabbed a small wooden desk (real wood!) which served as my computer desk while the consulting business lasted, and which (after we folded that business) became my wife's computer desk; she still uses it to this day. Also grabbed a couple of office chairs (which did eventually wear out, but we got many years of use out of them too).
As you can probably guess from the above, I have shelled out very little for office furniture over the years.
The priciest piece of office furniture I own is probably the desk chair my wife got me for Christmas about 10 years ago. The padding on the seat has gotten a little smashed down over the years, but that's nothing a cushion won't fix. Aside from that it is still in decent shape.