Old Things That Are Easier To Find/New Things Harder To Find Than Expected

Miscellaneous and Personal Stuff I Must Share
1

If I weren’t drinking and thought this out better, I’d have better examples. The two I’ll use are:

(a) Roman coins are ridiculously easy and pretty cheap to buy. Yeah, the Empire was huge, had a lot of commerce, and was around for a long time, I know. Still, $35 just seems cheap for, e.g., something this old (and admittedly beat up):

http://www.classicalcoins.com/product1933.html

(b) Video games made within the last 25 years can be ridiculously rare and expensive:

Because markets are pretty efficient, I’m assuming my question boils down to “why are some things scarcer than others,” so I’m not suggesting the prices don’t make sense or that things are readily available that are actually in short supply.

I’m more interested in things that surprised you to learn that so many had survived so long, or very few had ever existed/survived even though they once seemed pretty common.

2

I was surprised when someone was selling some thousand-year-old Chinese coins for a dollar each. Evidently, they were used as currency for centuries and are not hard to find.