I have a lot of vintage ammo - so much in fact, I have been using it at the Range. Ammo value really depends on what side of the counter you are on. If you are buying, it's "worth" a lot, however when you go to sell it, no one wants to pay you a premium.
A actually have many bricks of 22's I started using, 45acp, 38 spl. 32acp,25acp, 380 acp. shotshells, etc. that I am regularly using now. I know this may sound silly, but I actually get great joy out of shooting it and seeing how perfect it works after 60,70, 80, 90+ years! I can not remember ever having any failures to fire!
Hunting Pheasants and birds successfully with paper hulled shotgun shells from the 1950's thrills me! Shooting really good targets with old ammo just demonstrates how good it was made.
When I am at the Range and old timers bring in pristine unopened boxes of old ammo to target shoot with, I make them an offer to trade them for new ammo - they usually have no issues with that offer. That's where I got a lot of it. Some of the boxes don't even have a scratch or nick on them. After the ammo is used, I usually save the box. I would not go and spend any big bucks on vintage ammo because I have never seen it bring really big bucks, unless a true collector is seeking out a very rare and specific box of ammo. AFAIK, mine is just run of the mill from many years ago. Just looks cool.