What is Best Value Smart Phone for Money? Cheapest Plan and Data for Cell

What is the cheapest plan for Data service for a smart phone? What is the best value for the money? The most bang for the buck on smart phones can be found by searching the internet for discounts. At&t, Sprint, US Cellular, T-Mobile, Virgin Mobile, and Verizon have comparable plans but the cheapest can save big money. The Apple iPhone is the best but also expensive. Want one for under $100?
How about NONE. LG, Samsung, Motorola, iphone are best phones.