The reason the 5C didn't sell wasn't because it was cheaper than the 5S. It was because it was cheaper AND looked it too. My daughter has a 5, my missus a 5S, they look identical. The 5 was free on a contract and is £10 pm cheaper than the 5S, the S also cost £159 up front :( My daughter is more than happy with the 5, I gave her the choice between the 5, the S and the C, she said the S wasn't worth the extra and the C looked cheap and nasty.At the time (when the S & C were first launched) the C was more expensive than the 5 it was replacing.
For the record I run a SGS II as I can't stand iPhones.