Integrate e-commerce (possibly Zencart) with front end CMS website

I'm working with a client, who produces premium Sangria in a ready to serve bottle of wine, to launch a new product branded website with an e-commence function.

We currently have a static homepage with a shopping button linking into a Zencart platform which looks completely disjointed. It needs customisation and work to fit with the new brand and fresh, fun, festive summer feel of the product and need the website to have a CMS and simple ecommerce function.

We only have one product with 2 packages and we are considering the option to add another package in future.

My client loves Zencart because the platform works out all the shipping, etc so the package can easily be processed. Ideally, we'd like a website built into the front end (6 pages) linking through to Zencart though if there is a more cost effective solution still providing the benefits of Zencart, that would be great.

Can someone help me with a cost? I'd need this turned around in a few weeks.