I could have wrote what you did, and probley have in the past. I dont have a son, I do have a son in law that I think a lot of but have only seen him a few times as they live far away. Also like most younger guys he seems to be into the modern stuff and mine is mostly old classics. For now the best we can do is try to keep records that show what they should be worth as a guide.
I plan on doing a sheet of instructions with leads to gun chat sites and how to sell them like smiths to here, winchesters to levergunner, colts to the colt site etc. I am 71, and getting to the point I know I should be selling safe queens I dont use. The problem with that is from lifes experiance I know that as I sell them, a week later I couldnt tell you what I did with the money! Thats why I next to never sell guns or anything else. I have to work on this too!