drag and drop website builder

currently I am only gathering estimates to have a complete drag and drop capable webpage building platform created.

not WordPress, not Joomla, not Drupal.

I am looking to create a completely stand alone drag and drop page builder using the bootstrap grid system plus custom coding.

will include:
login/sign up system
page builder
page previewer
page publishing

supports

richtext
images
videos
embeddable script
forms
API integration

please provide a complete breakdown of price and time in your submission.