What appetite suppressants actually work?

I've had a serious problem with my weight for the last year. After grad school I ballooned up 40 pounds, and in the last 8 months have managed to take off a whopping 9 of them. I've tried it all: Weight Watchers, South Beach Diet, calorie restriction, tons of exercise. Nothing is helping. I've settled into a workout routine that I like, but without going crazy on all the specifics I just can't stop eating. And I mean stomach rumbles kind of hungry, not just emotional eating or eating out of boredom. I have a limit of 1600 cals a day based on the exercise I do and half the time my meals barely take the edge off. I eat nutritiously, low fat, good carb, fruits, veggies, no soda. I drink my full 2 liters of water a day. I've tried chewing gum, fiber supplements, you name it. The only thing left that I haven't tried is an appetite suppressant, but I don't want to waste my money on something else that won't work. Can anyone recommend one that actually does what it says, without costing an arm and a leg?