How about examples of the opposite? Not buying a vehicle and regretting it ever since?
I have walked away from many HMV's, either because they were too bad, too expensive, or I did not have the resources to buy, store and restore them. Most of the times there is a short-time regret, often one forgets the vehicle in question soon after.
But once I came across a ex-Swiss Army militarised CJ-5, used by a farmer so a bit scruffy, some bits 'n bobs missing but still in unmodified and basically sound condition. He wanted to let it go for less than two-thirds of a fair market value. I did not have the spare cash that day - still regret I did not beg, steal, or borrowed it and bought that jeep
H.