Actually Android isn't free. It is so patent encumbered (and hence requiring of royalty fees) that options like Windows Phone end up being a cheaper option.
This is a common misconception. Android isn't "patent encumbered". Certain OEMs have simply given in to Microsoft's legal threats and agreed to pay them to license certain Microsoft patents (regardless of their validity and/or relevance to Android, neither of which have been confirmed in a court of law) rather than burn money on expensive legal proceedings.
