The dollar amount spent is relative - $20 might be a lot for one person's budget while others could go through $1000 and not miss it. One thing that defines a hypomanic episode is whether it is different from what you normally would do. Another sign is goal-directed activity that isn't something you normally do (and anybody can decide to try a new hobby or something once in a while - the intensity and the impulsiveness have a lot to do with it). Also, how do you feel about it afterwards? Do you regret spending the money? What is the potential for painful consequences?