Bowflex Dumbbells

Hi MFT, hows it going, I was wondering if the products from t.v. that advertise ab rocket, bowflex gym, bowflex dumbells, red, and etc really work or is that just a way to convince consumers to buy their products. I was thinking of getting the bowflex dumbells but I'm not sure if it's worth it because their expensive online, but it has about 20 diferent pundages you can change. I have 20 lb and 50 lb dumbells but their certain exercises I still can't do because I need heavier wieght or lighter weight. What do you think I should do? I do not like going to the gym that much because you have to get a membership, pay a fee for every month, far away ,the weights and the equipment are sometimes old or broken, gets crowded, and sometimes bad service.