I don't remember ever seeing it on the "buy aircraft from Used Market" pages. It is there under aircraft maintenance, once the aircraft is delivered....
Probably why is because it breaks down the "repairs" into days out of service in most cases. Sami would need to add days into the delivery options as currently we can only select weeks as an option. Though I don't see it being really useful...
Aircraft below 75% would basically require a C check to bring it back to 100%, which defeats the propose of the extra repairs. Its a somewhat helpful feature if an aircraft is say "80%" to get it too 90+ for not that much money. Sometimes a C check is cheaper and faster... just depends on the condition and the number of days out of service.
However, I think the OP is probably thinking of aircraft that are 50/60% yet have "8+" months of a C check left. At that point, the time to repair would be greater then a C check and far more expensive. Basically at that condition, anything short of a D check is a waste of money.
So this feature wouldn't be overly helpful I would conclude.