Develop website template and associated images for a new community based website

We are in the process of launching a website which is similar to the eBay concept, but focus on specific industries in Australia. We have developed our website and have a website template, however we require a designer to really optimise our website so that it has the web 2.0 look about it. We want valid CSS layouts, we do NOT want nested tables! We want someone who will do a professional job! We require someone who can style HTML forms, create buttons, icons and create pretty workflow type images to describe how content works. We will provide examples of websites / screens we like the look of which we would like moved into our design. We already have a logo and colour scheme. We do not require any programming experience, as we have a developer who is doing the PHP, we require someone who is excellent at HTML, CSS and jQuery (and JavaScript generally). Our website is in the Yii PHP framework, so ideally we would like someone who is knowledgeable in how the layouts and templates work in Yii, however we can move the code into our PHP views ourselves if required. We will provide a list of templates and views required, and the successful applicant will design those along with the images they believe are required to make the page look good. We're programmers, not designers, so really want someone who can step up and really make our website look awesome! We would like a copy of all source files as well as html and css files so we can modify as required. We want someone who we can work with us for this project, and if we're really happy, we would like you to keep working with us for extra work we have fro this website, and the network of sites that we are releasing. Further information, and our current website will be given to interested applicants.