I paid $450 USD for a first gen X1 Yoga back in 2019 on eBay. Best advice is to either be patient and check eBay regularly or make friends with somone in IT close to you and get them to let you know when a local business is doing an upgrade.
thinkpads are interesting because they are heavy-duty machines that can be had for cheap on the used market. they are cheap because businesses buy them by the truckload and then offload them after three+ years and switch to Newest & Best. flooded market plus a buncha older models still around from earlier floods plus civilians selling their shit -> low price, otherwise nobody would buy them.
if you haven't got access to such a market, either by being around where they're being dumped directly or by having local businesses importing them in bulk and reselling them locally, then you should look elsewhere for value, as they're only interesting if they can be had for cheap.
e.g. you have similar options from hp (elitebook) and dell (latitude), they are also business-class laptops with durability and serviceability in mind, perhaps you can find those locally.
as an aside, you should skip all AMD platforms up until 5000 series; many issues (power management, GPU performance, etc.) especially if you're going to run linux.
I have two broken laptops with me right now - Dell Inspiron 5559 and Lenovo Ideapad S540-15IWL. Would it be economically sound to repair them both, as opposed to getting a new device?
ThinkPad
IBM and Lenovo ThinkPad laptop enthusiasts!