10x annual revenue I think flies by many investors books and wouldn't seem "outlandish". If need be you could probably meet somewhere in-between 5 and 10x. 2x seems like too low of a multiple.
I don't know if I agree. 10x seems to be the common theme a lot of people quote but I've never personally seen a statement that says this is an established standard (which books are claiming this?). I think there are multiple factors to consider when buying and selling, and claiming 10x annual revenue is standard is fool hardy.