I have an Android dev phone that cost £19, no contract, about half-to-a-third the price of a then-equivalent second-hand iPhone. In third world countries even a £19 device is worth stealing, as a friend of my partner experienced.
Vodafone sold it (pay as you go, no contract) with only their brand visible, but I think it’s an Alcatel device under the paint. The model is no longer being made, but their current cheapest model is almost as cheap.