Volvo V40 front right coil spring repair, to do or not to do when selling?

volvo
v40

#1

I am selling my 2000 Volvo V40 and recently took it to a mechanic because it needed new brake pads, a new tumbler (the car could not start) and new lights. These repairs totaled $730. About 30 minutes after I paid for the bill over the phone, the mechanic called me back saying that he had heard noises coming from the bottom of the car while driving it in the car lot. He said that the front right coil spring broke and needs to be replaced. He also said for me to replace the other coil spring to make the car more ‘balanced and aligned’.It costs $430 to repair one coil; $730 for both.

Question: As I am repairing this car to sell it, what should I do? Is it necessary to repair this coil spring? If so, just the one that broke or both? How did the mechanic miss this problem? Should I go to the garage to talk to them in person or not? I’m not sure what to believe or to do in this situation. Any help would be greatly appreciated!