I’ve three which I still regret. Two not buying, one lost:

When the US economy was unraveling in 20-teens, I had the opportunity to buy first a 1971 Pantera in factory teal (look the color up. It’s beautiful) for $29k, and later a 1988 Testarossa for $40k. I passed on them because buying either one + storage would’ve drained the little reserves I had (and added a car payment) at a time when I didn’t know how much longer my company would be in existence... don’t tell me what they sell for now. I’m aware, and I try not to think about it.

The car I lost: 2006 Volvo S60 R Manual. Bought from the second owner with 55k miles. Had every receipt for everything done to it from new. Rear-ended a guy at 10mph (lss: I came around a blind corner at the speed limit, 60, and ahead of me was a guy coasting towards stopped traffic that I couldn’t see, and didn’t realize he was coasting until nearly on top of him. Told cop what happened, he said he was braking, cop gave me ticket), but it was enough to shatter the headlights, and crack the front fascia. It doesn’t sound like much, but the cars are so rare, that there weren’t any used parts available, and new parts from Volvo were going to be more than the car was worth. The real kicker? Insurance company wouldn’t let me buy it back, and so I couldn’t rebuild it on my own dime.