1860 cent through dollar traded for a PCGS VF-35 chain cent. I have an image of it somewhere around here. I'll post it if I can find it.
I had to fight for my collection in my divorce noting that it has been collected by my family for over 140 years and that she had no claim to any of it. Cost a bundle, but she didn't get any of it.
I did something similar when 18yo. sold a 1700's copper cent for a couple hundred bux.(all they went for then-60's) Now worth a couple hundred thousand,easily.
Hahah...I had a ton of hockey cards from the 1990s that I paid to have moved back to NC from Calif when I moved in 2000. I could never sell 90% of them and nobody would take them as a donation for kids so I finally just gave them away last year. My other big booboo was selling all the proof and unc ASEs I had bought over the years back about 8-9 years ago when I needed some money for a trip to Thailand. Oh, how I wish I had kept all of them....they went to one of those stupid gold buyers at a hotel over a weekend.
I think the dumbest decision all time is collecting coins beyond what I found in change and circulation as its cost me a LOT of money!!
My biggest mistake was buying the 5 coin ASE anniversary set off Art & Coin TV in OGP. I'm so far underwater on that set, my grandchildrens, grandchildren might be able to break even and I don't even have kids. I was just getting into this hobby and well, I was naive. I cringe still thinking about it.
Buying a PCGS 1901 P Morgan that was Unc. Details, Questionable Color with luster showing under the color. Thinking I could break it out and resubmit with the AT removed for at least a MS60 grade. Came back AU Details, Reverse Improperly Cleaned. Oh well, worth a shot.
As a 15 year-old newbie collector, one of my first eBay purchases was a Trade dollar from China. I was super excited to think that I had won a hundred-dollar coin for $0.99 (+$15 shipping). I only had to learn that lesson once, and I consider myself fortunate for learning it so cheaply.
I most likely am still making coin mistakes. But I think I have learned a few things. Only time will tell.
Oh, I guess I was looking up the heraldic eagle, $11,000 for a 1796 small eagle variety sounds pretty good if you can afford it.
When LP1 came out I thought I would order two of all four types. After my order was filled while many were unfulfilled, I ordered five of each of the other three types. I still regret not ordering 5 of LP1. On the flip side, I was speaking with a dealer friend about the LP1 and he shared his regrets: One was that he had accidentally placed his two orders using the same card for payment, so one order of five was cancelled by the US Mint. The other was that he threw the five sets he did get on eBay with a BIN of $50 without checking trends and was at first shocked and grinning at their swift sale only to see he pulled the rug out from under himself with a BIN at half the going rate at the time.
Saw someone making one yesterday. Can't remember which one but someone had bid a coin up 20 bucks more than the BIN price.
Well, I have made so many that there is no way that I can remember them all, but one major one comes to mind when I purchased what I thought was a very rare and exciting coin online from someone who told me it was authentic.....derrr. Many apologies about the photos. I have not learned how to get the photos to appear as they should just yet. and I am not sure how to get them to be so close in detail either... still learning.