I have a Samsung Galaxy Note on RingPlus (Sprint) 700min/700text/750MB-4G LTE - cost: $0.00 month. Two Apple iPhones on PagePlusCellular (Verizon) - cost: $7.00 month. Nokia Lumia 1020(WIN 8) on H20 Wireless (AT&T) - cost: $4.00 month. Needless to day, I don't use my smartphones that much. Mostly for cameras and apps. Sprint is primary and more than covers my needs. If no connection, then AT&T or Verizon.
When I had an AT&T Sony flip phone 10 years ago, I paid $50. month. How things have changed using MVNO.