Payment System - php, mysql

I will need to have a developer finish up 2 projects - both involve integrating a payment system, debugging, script configuration/modification and some site design. It requires expert level execution, attention to detail, following a project schedule [meeting a deadline] and previous experience implementing similar payment solutions for direct payments. It will require a demo of at least 3 different similar projects that include a payment system component. WARNING: To demo a project of a certain quality and develop or deliver a project with a different or lesser quality than what was demo'd will be grounds to terminate the project. Thorough documentation is important. OTHER DETAILS: The first project is an order form that needs to have a direct payment system integrated. The other project is a payment form with option of making direct payments.