My greatest treasure is a 1911 made in 1750 and carried by George Washington at Valley Forge complete with photos of him wearing it, and you would not believe what I paid for that one.
Past that, more mundane guns would be the 1903 Frontier Six Shooter out of an Arizona estate, which was traded at profit on a 1957 SAA..45Colt 4 3/4 nickeled NIB, which was then sold for a tidy profit as what I really wanted was a shooter, and profit used to buy a 1971 SAA b/cc and otherwise identical gun which has been a constant companion.
Had a near perfect 1913 1911, but same as the SAAs, really wanted shooters, and it was sold at a profit with profit used to obtain a stainless Colt 1911 which has been a constant companion.
Have owned quite a few much older long guns ranging from flintlock to percussion to early Winchester and Mauser, but them both off topic and now traded/sold with only one remaining, a beater 1894 6.5x55mm carbine as, tah dah, a shooter.
Having already owned most any firearm ever wanted, through great sacrifice, and then that getting stale, all which interests me today is shooting and keeping things simple, and if it not destined to be used on a regular basis and go places besides a range, then it doesn't get bought, no matter how neat/cool.