It's just another form of capitalist realism to think that a magical feudal society would have a well developed money economy like a capitalist society to the point where everything is a commodity with a price tag that can be sold on a market that's always nearby. In an actual magical feudal society, stuff like magical swords would simply have no monetary value but be weapons that could only be wielded by certain strata of society (nobility, knights, wizards). Serfs, tradesmen, traders, and so on would be forbidden from touching let alone wielding a magical weapon on pain of death. There will still be an exchange value of the item based on the labor hours that was used to create the item, but it wouldn't be something that you would buy or sell in a store.