It's not quite that simple. You've got to consider the price of the phone on and off the contract, the price of the contract, monthly usage, prepaid value, expected life of the phone, etc.
I bought my £100 phone 2 years ago with £10 credit. Still got about £4 remaining on it (clearly I don't make a lot of calls). If I'd bought it on a contract I would be down double or triple what I paid.
I bought my £100 phone 2 years ago with £10 credit. Still got about £4 remaining on it (clearly I don't make a lot of calls). If I'd bought it on a contract I would be down double or triple what I paid.