Not sure what you mean by the last part but since you talk about the value of things 30 mahogany wood is worth 10 guild coins. If you get 50 instead of 10 it seems like the quest is worth doing? Unless your guild specifically avoids doing guild quests I'm sure they'll be happy you helped everyone earn more coins and help you with trades and possibly give you the things you have to pay if you are short. Seems like win/win to me.