Good point @ the X201...they were really well-made and durable. I own two ( 2 ) X200T ThinkPads, and they are simply exceptional machines. I will say that finding a battery for an X200T is no fun...seems most sellers are asking around $50 USD, and that seems high to me. My guess is that rebuilding one of these batteries would be not-too-difficult, and I may look into what it would take.
Michael.
I rebuilt one for the T60 which wasn’t too difficult. Hardest bit was getting into it and doing the BMS reset.