What is a really cheap and easy way to lose 50 lbs?

Diet. Above all else, diet is what works best. There are various regimens to consider, from low fat diets to low carb diets - find which works for you not only in the short term but something that you can continue doing so you do not regain weight. Speak to a nutritionist to help you establish a good diet.
Exercise too. Proper diet and exercise, good sleep patterns, self control, reducing stress, having these and some accountability. It's a lifestyle change and commitment, not a quick fix.