The price jump on old Stanley thermoses is nuts now

I used to grab the green steel ones for five bucks at any yard sale in Ohio. Last weekend, I saw a guy ask eighty dollars for a beat up one at the Springfield flea market. That change happened in maybe three years, tops. It's all because of those 'buy it for life' videos online making them a trend. Now every reseller thinks their rusty thermos is a gold mine. Anyone else seeing this with other basic old tools or gear?