im 34 and i have seen many $500 bills and have a few of them in a safe , I have even seen a 10,000 bill 1 time in my life. when i did see it i thought my eyes where playing tricks on me. I was 15 and it was sitting in my fathers bedroom. at first i thought it was a $1000 bill then when i saw 10,000 i was like what the hell a 10,000 bill. I just was reading about how the bills them self say for trade to gold. due to at the time gold was = to money so thats why i guess bills are more value then before. I don't know why a $500 bill is almost worth double but i guess it would have to do with something it says on the bill it self.