Correct. The expected benefit of an action is the value you place on the intended result of the action reduced by the probability that the action will produce the result. In the bookstore/ice cream example, you reduce the value you place on getting the novel and the value you place on getting the ice cream cone by the same amount, so the expected benefit depends on just how much you value each result.
In general, as the value goes up (or down), and as the probability goes up (or down), the expected value of the action goes up (or down).