They were so many, this page is so short.
I traded a cheap .25ACP Buffalo pistol to a WWII vet who wanted it in exchange for an S-42, G date Mauserwerke Oberndorf P-08 Luger (matching numbers throughout, no loss of blueing or wear, literally "Pristine") with matching, serial-numbered Hanel aluminum-based (no wood)) magazines and its own custom holster. And a year later, I traded that Luger for a bunch of reloading gear and components, and yeah, today's value on that gun would buy me a new BMW. That was the first - I am still kicking myself, but then I was young and uninformed.
1965 - I bought a new Winchester 94, 30-30 and a decade ago I gave it to my grandson.
1966 - I bought a brand new, in the arsenal box, 1903-A3 two-groove Remington barrel, that my neighbor bought from DCM and decided he didn't want it anymore, but it was sold a decade ago for enough to get into AR's.
I gotta quit here - my tears are in danger of shorting out my keyboard.