Build similar site like nationbuilder.com

We need a similar portal built with the features like in [login to view URL] Please review this thoroughly and let us know which platform you would like to implement. Important features: 1. Users can select Templates from a set of predefined templates. Buy template using Cart, payment gateway. 2. On selection, create a sub-domain automatically. 3. Surveys, Polls, Blogs etc., shall be created. I don't need Phone features. Please ask me any questions if you need. Take your time and bid please, "No change in Pricing acceptable". Please be realistic and don't copy paste.