Build responsive website with retail functionality

We are a fashion and technology startup looking for web designers / web developers to design and develop a responsive website that can be easily maintained and inherited by an in-house web developer. This is a two-phase project: for the first phase, we will in the near term need a landing page for our website to announce our product in a visually interesting way. For the second phase, we will need online retail functionality and updates to our website and new pages as our startup grows.

Please provide a quote or estimation for the first phase of building a basic website and landing page for us, as well as plans for the second phase (for website updates / changes). Thank you.