.net project development firm

We are looking for development shops to help with the development of a new web portal on .net platform. Looking for a web developer (preferably a web development company) for a building a website from a prototype. The portal is extremely data intensive and requires data saving into a database. There are ecommerce functionalities including credit card processing, session maintenance, admin modules for site content control, google maps integration, etc.. Expertise in configuring data feeds from external APIs and database design and programming are also desired. Preference is given to a company that also has expertise with Salesforce integration, as we would like to give more work to the company should this project go well. (Sales force is not required for this current project.) Please write back to us with samples of data intensive website you have developed.(Applications without this will not even be considered) We would like to schedule a tech interview with the developers and also have 2 references of your previous clients. We would like to communicate with them before handing this project. Because this project has a long term engagement potential, we want to be sure of whom we pick.