Honestly I am highly dissapointed with this book, even for the price. If you're thinking of getting this, buy the first one instead. Even better, get "Fantasy Fungi", which really shows this up, with more interesting descriptions and uses, more detailed descriptions, and better environment/habitat descriptions.
Many of the goods are things like millipedes, fireflies, minnow, earthworms, dandelions, which not only are typically priced at 1cp - why would an adventurer ever bother with such a small return? - but are exceptionally uncreative and just a bit of a let down, honestly. This could be redeemable if the ones that say they are used by "alchemists, potionists and wizards" gave a good reason for their use, but they really don't. I'm not sure why these were considered to be a "fantasy commodity" i don't see what is fantastical about them or what makes them a commodity... honestly, i doubt i'd even have an NPC village town in which these were of interest.
Then you also have to account for three different double ups - a couple of animal products that are the same, as well as some ore that has near identical descriptions, and then utterly no reasons given for their price.
I know the price is very good, and there are a couple things that are interesting - but thinking about it, I'm not sure if it was worth trawling through for the gems. As I said - better stuff out there, even for this pricetag. I'm just not sure what the creator was thinking with some of this stuff. A little lazy.