I have been resisting writing this reply for days but I can't hold out any longer...
No, I would not buy this, nor any other "App" that tells me how to "forage" or "survive"!
And here are the reasons why;
1, I am very old school - I would not trust any battery powered device to hold sufficient charge to make the information worth-while. Not only that but it might encourage folk to try to remember the edible amongst the toxic - without really "learning" which is which. I have a mobile phone that has "Apps" on it but I don't know what most of them do - I would rather learn about that topic that interests me and not how to read about it on the smallest screen that I own.
2, Toxic look-a-likes, some deadly species can appear visually very similar to edible ones - without a "percentage of certainty" or many warnings that reference each species and those that it may be confused with.
3, Categorisation - There are numerous reference books that are categorised according to out-dated information and ideas, if your information appears confusing to a reader, it might not be the success that you hope it to be.
4, If I were to buy any information about Fungi, I would want to see that it is endorsed by a well-known name.
5, Price, Cost & Perceived Value - when compared to the books I own, and have searched for and treasure - a "£3 phone App" is something that I would treat as "disposable" information - something that I would not care if it became corrupt or got lost.
Sorry to be such a negative responder - but if it is market research you are after.....
Ogri the trog