PrestaShop theme development

Hello I am developing an eCommerce website using PrestaShop. I have about 20 pages (in .psd format) designed in Photoshop. I am looking for someone use them to develop a theme that I can install as any other theme. I will add functionality to the website myself, it's only the themes that I'm not knowledgeable with. I need a list of things that have to be done develop the theme and an estimate of time and money asap. Thanks a lot for your help.