Generally the T series Lenovo Thinkpads are the business build quality, generally repairable for some things. But there are still complaints about funky keyboards and weight.
I had just checked recently and the great Arrow Direct, Lenovo Thinkpad refurbs on NewEgg are all gone. Even the seller search listing for the category is gone. That would have been the place to go. I got two great machines that way, a 3rd gen X1 Carbon for $414 and a T540p for under 200.
I found out why the T540p they sent me was new uncirculated. Battery latch allowed some slight movement and it would disconnect. I had Arrow Direct issue a $25 credit, the difference between the grade A and grade B, and put a piece of HD duct tape across the battery and laptop bottom, so I am very happy. The T540p was so nice there was no way I was going to send it back, even with the funky keyboard.
It could be something to do with the trade war that made the good refub inventory disappear.
I would not buy someone else's used laptop, but if I could get those really clean and cheap corporate off lease refurb Thinkpads, it's a no brainer that's what I would do.
I was going to try a $450 Asus consumer grade beater, but the X! C is just so nice. I generally like Asus for my PC build parts.
Laptops take a beating and are not expected to last (10 years). If I could get the same deal for grade A Lenovo refurbs, that's where I would go.