Google Checkout using XML & Order Processing API

We have just signed up with Google Merchant, Checkout and Shopping. At this time we need a developer with expertise in Google Checkout to create a One Page CUSTOM Shopping cart integration as described here: [login to view URL] When finished we must also integrate Custom Order Processing using XML only. Though though version 2.5 uses Java, we are more comfortable with PHP at our store (version 2.4) but will listen to your expertise on this subject. This is NOT a standard Html simple integration so please know what you are doing before accepting this project. We have a sandbox account created with Google Checkout and have the Sandbox merchant ID / Key so are ready to move forward. * We need a "One Product" shopping cart that displays the product via html/php * We must be able to submit the product for purchase to Google Checkout using our sandbox account * We wish for Order Processing to be done server to server They should have experience with all things listed on this page: Our goal is to build our own shopping cart in the future but need guidance at this stage to create small, simple but working model of a single product.