The social structure of a fantasy world need not be absoutely parallel to any historical example.
True enough, but the further you go from a historical example - our only closest reference to 'reality' - the harder it is to suspend disbelief and actually get into the game world to a significant degree. Those of us with a high level of ability in 'suspending disbelief' could likely have a great time with a very, very unrealistic system. I, unfortunately, am not one of those folks, and so I very nearly require a plausible social structure and economic system before I start having fun with a game world.
When I still played D&D on a regular basis (instead of semi-regularly like I do now), I had a four step process to get the economics back in line:
1. Reduce ready cash by an order of 100. Coinage in medieval life was actually pretty rare and tended to be accumulated in the hands of the nobility. It wasn't until the rise of the wool merchant middle class in England that most commoners had access to more than a few coins here and there. The 90% of the population that lived in the manorial villages held almost all of their cash in kind, which led me to my next step.
2. Remembering the total wealth of the person before step 1. I substituted wealth in kind. Wealthy farmers had land, chickens, pigs, a croft that produced vegetables and fruit, an ox, a couple of cows, a larger cottage, multiple sets of clothing, etc. Totaling this wealth made a successful farmer very comfortable indeed, but with almost no portable wealth other than the animals. IMC, city folk were much poorer, with unskilled labourers simply not making it by without steady work. They had more coinage, to be sure, but almost no food, did not own the roof over their heads, had one set of clothes, etc.
3. Reduce the number of magic practitioners. Everyday magic makes it all but impossible to balance the economy. IMC, most villages remembered stories about magic users, but most folks had never seen one with their own eyes and would likely have been very suspicious of one if they had - power is a very frightening thing to those without it. There were magical guilds in the larger cities, but they might only hold a couple of dozen practitioners and only a small handful of masters. Priests who could actually cast spells were really, really rare and were almost mythical in nature ... most priests couldn't work those kind of 'miracles' and were just commoners with a much better education.
4. Use the guild system. Guilds set prices and make the GM's work a zillion times easier by essentially limiting the price fluctuation of the most common goods. It is much easier for a GM to decide a supply and demand price for the luxuries and rarities when needed rather than to have to do so with every commodity in the market. Adjust down 10% for 'close to source', adjust up 10% for 'far from source' and adjust up 20% for 'really far from source' and the GM is essentially done as far as a commodity is concerned.