A purchase shared with another person needs agreement about its ordinary life after the excitement.

The buying is the exciting part and it lasts a fortnight. Everything after that is maintenance, storage, insurance, who uses it more, and what happens if one of you stops wanting it. Almost every argument about a shared thing is really about terms nobody set at the start, because setting them would have spoiled a pleasant afternoon.

Before going in on something together, spend ten minutes on the dull questions. Who keeps it, who pays for repairs, what happens if one of you wants out. It is a much easier conversation before the money changes hands than afterwards, and it protects the thing you were both looking forward to.