Hello,
Can you provide a link or a short demo of your existing application? It will give us an idea of the type of functionalities you'd require. Have you developed the web services? We will need a rough wireframe/outline of the screens so that we can bid accordingly. We can prepare a professional proposal according to your requirements with our final quotation as this is just a cover letter.
We are a company based in India with a team of dot net developers and designers. We have experience in building online stores, job portals, travel portals, saas applications, business websites, portfolio websites, service providing sites, booking engine, taxi dispatching app, mobile sites, mobile responsive websites, etc. So, if you want to see our work we're happy to share.
We believe a discussion about the project will be convenient for both of us to decide anything so if you are interested please get in touch.
Regards,
OKTeam