495419 Modx - Ecommerce Feature

My client has a 5-page website with Modx CMS. We want to add an e-commerce feature to it. It will be one button, when pressed goes to a one-page shopping cart. That page will collect the shipping and billing info and of course the account info and accept a bank payment gateway. Prior experience in Modx is necessary. Show me what you have done. Ecommerce in Modx even better! Timeline is 3 weeks. Please quote me how long it will take you and how much you will charge. Be firm - deadlines have to be firm. You will NOT get paid if project is not delivered in said deadline. Thank you. PS You will get exact layout of the checkout page once your bid is selected. Also do not ask me for the URL of the current site unless you are chosen.