Recomendation about web features

We are looking for someone/company to recommend us very reliable & unexpensive web features/solutions to include in a e-commerce site with helpdesk, customer service and e-commerce. Specifically we need a recommendation on good & unexpensive solutions, already available in the market and VERY reliable for the following: - Shopping cart - Helpdesk with email piping - Billing information feature - Order status - Secure Payment (e-commerce) The person/company who recommends these will need to have full experience with these & have used them already in many/different web pages. Any other features which are not included here will be highly welcomed. These features will be included in a new web page. We will give you more details to those who bid & request so.