I'm on a contract where I "pay as you go," for voice minutes and texts, and, pay £8 per month for 4GB of data.
I make calls and send texts freely, without worrying about their cost. Though nowadays with WhatsApp, iMessage, FaceTime and stuff like that, I end up spending very little on these.
In total I usually pay around £10 per month.
Work provides me with a free handset that gets upgraded every three years, so that doesn't cost me anything.