Grain Into Gold is a very solid attempt to introduce a level of economic realism to fantasy games. The writing oft times has a tongue and cheek tone to help break the monotony of discussing economics and does a decent job of helping engage the reader.

The authors certainly rely upon guesswork, but it is logical guesswork. Still, this can easily leave the reader doubting the validity of the math when looking at the example price chart at the back, especially given how radically different the values are from most games. Even considering the margin of error introduced by the guesswork, when stopping to think about the numbers, they made far more sense to me than those in most gaming books.

Perhaps the biggest failing is that Grain Into Gold focuses almost exclusively upon a western market, giving little to no consideration for crops and goods outside of the western mindset (e.g. no rice).

Perhaps the most misleading value is actually gold. Though the authors admit that their gold estimate is inaccurate, they stick with it, keeping a 1g to 10s ration that is popular in most games rather than a realistic ratio. This skews some end values as a result, most notable that of gold.

Perhaps the area with the most room for improvement is the price charts. Where some items, such as clothing, are covered in extreme detail, others, such as weapons and armor, are not. Given that most gamers more readily want to know what a sword will cost than a heavy wool sweater, this seems to be a bit of an oversight.

If you set these flaws aside and focus on how the prices are derived, then you can adapt the methodology to estimate the value of goods in both a medieval setting and beyond with reasonable accuracy. This is the greatest take away from the book. Lessons are provided for everything from walnuts to chain armor, discussing everything from harvesting to manufacturing to transport and taxes. It all starts with how much surplus food a farmer can produce. If you pin your economy to that and follow the logical steps from it, then you are golden.