Creating a Website Payments Pro Plugin

We need a plugin to be developed for Website Payments Pro from Paypal which connects to any version of our DJ Classifieds Component, currently we have Joomla 2.5. This plugin and payment method has to be then connected to our promotions and 5 identical Joomla Classifieds sites. All sites will then be tested for whole payment process. Here the developers link [login to view URL] The plugin is to be handed over after development to us.