Hello Hassan:
I have developed a simple email provider for my customer's store, and posted it along with detailed instructions for installation and development. The development instructions include the _dnnStub project that has become popular in the DNN 3.x community as a way to speed up compilation and debugging of DNN Modules:
http://aciasoftware.com/Portals/0/EmailGatewayProvider.zip
If you have any problems downloading the file, post back to this thread.
For search purposes: This solution addresses the issue whereby there is no simple checkout provider for the store that doesn't require an account with either authorize.net or paypal (a much better situation than a store that didn't have that built in already !!!) and the user's customer will be doing Purchase Orders or something to that effect for their store.
Also of note, I developed a store module that was for sale on Snow Covered and actually did quite well (you won't find my name associated with it as it was sold by another company) in any event, the module is my property, and pretty much obsoleted by this one. Although written in VB.net, it did have a complete management capability as well as the ability for customers to view and print any previous order. I would be happy to donate my source to the project if that would be beneficial. Another enhancement I made (which was incomplete I believe) was to create create a gallery module for product photos. My store (like this one) used a picture.aspx file to read the bits of the picture from the file, cache it into the application cache, and display the cached bits. The problem is, with big stores, this could start to eat a lot of server memory. I think the best solution is to have pictures scaled by the administrative upload process, and simply read from the file system by the server.