WordPress Drag & Drop Page Builder Plugin - URGENT

we need a professional wordpress developer to create a drag & drop page builder/composer from a scratch. we have premium wp themes and this builder must be compatible with them and their shortcodes. It should work similar to popular builder plugins like [login to view URL] , [login to view URL] , [login to view URL] but it cannot be any copy of them or any others!! User can select in the editor view the classic wp mode or the builder mode. Design of the builder must be nice flat and have color scheme of our company main website. WE DON'T ACCEPT ANY KIND OF COPY FROM ANY OTHER PLUGINS! 1) Builder must support shortcodes plugin 2) builder must work in a classic wp mode and the builder mode 3) must support widgets, so user can add widgets through the builder 4) must be responsive in front end and backend too 5) i want it to work in the edit post mode as well as in the post view mode 6) i need this plugin to work with both my premium themes 7) something nice flat design PS:- READ BEFORE YOU BID. STRICT BUDGET SO DONT BID OVER $600. I NEED ONE PLUGIN BUILT FROM SCRATCH..... I DONT WANT A PRE-EXISTING PLUGIN ...... I WANT U TO BUILD ONE WHICH FULFILLS MY REQUIREMENT AND DELIVER TO ME ALONG WITH SOURCE CODE.................. IF I NEEDED AN EXISTING ONE I WOULD GO AHEAD AND BUY IT FOR $30 .....