Just bought all three books, read through Managing Business and Mass GoldFarming, just getting started on OSRS Billionaire. From the first two guides I can already say this was a very worthy investment and you really do learn things no one has mentioned anywhere else. I think my favourite part of the guides so far is realizing that you really can't fail following them unless you have no motivation, but that applies to all entrepreneur ventures. I'm pretty excited to start my own gold farming journey, and I'm glad I spent the money.