Another way of looking at it is that US median household income per person is about 28k per year. You can buy a cheap car for 10k, or 130 days of your per-capita median income. A potion of healing costs 50 person-days of modest lifestyle support.
As the share of "disposable" income -- here, I mean income spent on not-food and not-shelter -- is likely to be lower than a modern US society (which is crazy rich), this means a potion of healing is more expensive than a new car.
So a "middle-class" person in a D&D society might buy a potion of healing as a capital purchase they can make every decade or so at 50 gp per pop. On the other hand, a automatic defibulator is cheaper than that to most US citizens, and few people have one in their home.