Come on, things are worth what people are prepared to pay for them.  Full stop.
That may (or may not) be more than the seller bought them for.
I might let something go for buttons because I can barely squeeze into the garage and the car's just packed up and the Mrs is nagging me.  Lucky buyer.
Likewise I might pay over the odds for something because it is the last bit I need to finish or repair something.  Lucky seller.
You win some, you lose some.  When you are a kid you get what's fair.  When you are an adult, you get what you negotiate.
If you don't like the price, don't buy.   If everyone else agrees, prices will fall.