Does the extreme gold guide work

Yes, it provides many ways to effectively get money. Is it worth the price? ABSOLUTELY NOT. I have found that most of the ways explained in the book are easily obtained by simply asking a player in-game. For example, you can collect cowhides by killing cows near lumbridge, and sell them in bulk. For members, get level 10 crafting, and turn flax into bowstring. Flax can be found south of camelot. Or, you can get 150k+ an inventory by collecting rannar where the druids are in the relleka dungeons. As you can see, to get "rich" in any online game is easy, just ask around.