My highest dollar value gun is also my most valued sentimental gun.
It was given to me by wife's grandfather just a couple months ago, and since I do not come from a gun family, it is the only family heirloom gun I own.
It is a Browning Hi-Power Safari Rifle, chambered in 30-06. It is from their first year of production and carries a 3 digit serial number. It is in 95% condition with some beautiful wood on it.
Every month, an estate auction company near me has a gun auction, and they built up quite the reputation as a gun appraiser and gun auction house. When I was up there last time looking at the wares for the next upcoming auction, I had him take a look at it for me. He valued it at about $2,000. Most early Browning Hi-Power Safari rifles in 30-06 go for about $1,100-$1,300 he said, but expected that the 3 digit serial number would add a bit to mine.
Doesn't matter to me though, the only way that gun ever leaves my safe is the day I give it to my child/grandchild.
Every other gun I own can be readily bought at pretty much every gun shop in America, and most for well under $1,000.