I would like to see the detailed Proposal,(not just high level cost) outlining the solution which you are going to build,along with detailed breakup of activities and Milestones.
Like Overall Architecture of Stacks (components), GUI Design/Development for Store App, User App & Wed Admin with features which you consider (like SMS, PayTM Integration,etc),
Design/Development of Database,
Implementation of Business process, Testing, Deployment for Testing and Deployment for Production, Support, Warranty, etc. Keep it as detailed as you need to. Also write your scope and Out of scope items, with what you need from us as Dependant items.