I often hear people misusing the term expensive. Mixing it up with the term costly.
Expensive is when what you (can) buy is priced higher than the value it potentially delivers.
Costly is priced right for the value it potentially delivers, only in your opinion you have to pay much to obtain it.
Much is culturally defined.
The definition of much is different on every street corner, in every city, in every family, in every other context.
What one calls expensive, the other calls a bargain.
Costly is a fact.
Expensive is a decision, about potential value.