I entrust myself for the web application development to two powerful open-source platforms: Umbraco e nopCommerce.
Umbraco is a very big cms whose built-in functionalities allow me to realize websites in a very easy and speedy way. nopCommerce is a very complex but a the same time completely moldable to the very different needs e-commerce.
There are plenty of opportunities about the net, contact me and we will discuss your requirements and the best way to develop them without obligation.