A while back (before I got burnt out on it) I went and did a bunch of amateur research into medieval prices and made a set of price tables that more accurately reflected the actual medieval prices of goods and services. I did this because I was working on a big custom rpg setting, and I wanted to have realistic prices for things if my players decided to carry cargo from place to place in their boat while adventuring. Towards this same end, I attempted to make a simple economy simulation so that different countries in my world would have different prices for goods, but google sheets proved too unwieldly to do this in, so I abandoned the attempt. I didn't want all that effort to go to waste though, so I figured I'd post it in case others could get some value from it. Thus I present:

The SAMPLE tables

Spoiler: How to use the tables
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Just stick to the first section that has all the base prices for commodities. If you're a GM then maybe check up on the speeds/prices/capacity of the transport methods and the wages of the various professions, but for the love of all that is good don't try to mess with the price calculations. It's been months since I built this thing, and I don't even remember how half of it works. You may also wish to check out the historical source price section if your curious and you don't mind it being in the standardized currency.

There's a table at the beginning for the conversion of the custom currency being used to a standard cp/sp/gp system, although the value of those coins doesn't actually match those from D&D since all the prices are different
(ie. longsword in D&D costs 15 gp, and in the SAMPLE tables it costs 8 small gold coins and 5 small silver coin)

Spoiler: How accurate is this?
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Not very accurate. I mean, it's more accurate than anything you'll find in a D&D book, and it (arguably) portrays an accurate view of peasant standards of living, but also peasants of feudal Europe wouldn't actually have physical coinage money in the first place (by my understanding), and I'm pretty sure that any historical economist who ever finds this will die spitting in rage as their corporeal form melts from the mere sight of it. Given some liberties I'd consider these tables a useful tool for any GM who wants a grounded, semi realistic setting, but don't ever try to use this to win an argument.

Spoiler: Methodology
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I basically grabbed a whole bunch of medieval price lists, used bread to standardize the prices into a single currency (denoted as ✧), then used what historical sources I could find to alter the prices of individual items and propagated the implications of those more historical prices into the rest of the price lists as best I could. This propagation partially took the form of putting as many items into a sort of production flow chart as possible (thread becomes cloth becomes clothes) and comparing the prices of various items to the amount of material and labor (and price of labor) needed to make them to help fix inconsistencies.
Wages for a large variety of professions were calculated by creating a scale of rough 'classes' from unskilled children to professionals, assigning the historical jobs to a place on this scale, and then using the historical wages to get a value for the income of each place on this scale. Each profession was then assigned to a place on the scale as well, and had its income modified depending on how rare the profession was.
These wages and prices of food were then compared against eachother and modified until they seemed relatively self consistent, with the assumption that roughly 70% of the population were farmers. This was then further propagated into other factors, such as the average farmer household size, the size of the average village, what portion of the population were knights, the cost to rent an acre of farmland, ect.

Basically: the calculations are a mess, but the economy is self consistent and arguably matches medieval demographics.

Spoiler: Problems with the tables
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I gave up on finding the weight of all these items and materials, so everything just has a default weight of 1 lb. I likewise gave up on trying to figure out how much time and raw materials it would take to make each item.
The economy simulation tables are... useable. They're big, and unwieldly, but if you scroll over to the right there are columns for supply and demand that you can use to kinda see what the price would be in various locations depending on supply/demand and the transport costs between locations. The big problem with the economy tables is that they are a nightmare to expand, so if you want to compare more than 10 locations, or compare a new item/material not currently listed, it's a huge pain.

What Next?
I would like to improve these tables and take this project further, but I have realized that Excel/google sheets just isn't appropriate for a project of this scale. I plan on converting the project over to a custom program, but it'll be a while before I get around to that.

I would, however, love to hear peoples thoughts on what I currently have, as well as any recommendations for improvements, corrections, or sources I can look at when I get around to making the program.

As for the tables themselves, I don't think I have it in me to work on them any further, but you may feel free to leave comments or make and edit your own copies.