Buy virtual product & edit details at any time - Simple eCommerce

I am building a website that will allow a user to register / login and purchase a virtual product which will be a virtual service. There will be 1 package to buy that will offer 2 virtual items. The user should be able to buy this package then the 2 virtual items will appear in their account. After the items are purchased there needs to be a series of inputs for the user to fill out, all text based, for each virtual item. Those values will need to be stored in a mySQL database when saved and most importantly, I need to be notified when the values of the virtual items are modified / saved. In other words, if a user buys Package A which includes Virtual Item 1 and Virtual Item 2, after purchasing they need to be able to modify specific details of each virtual item and save the information. Once the information is saved I need to be e-mailed or notified somehow of the specific change. The user also needs to be able to purchase more virtual items to be added to their account. They should be able to buy the same package as many times as they want which will add the virtual items (which are editable) to their account. So if they buy Package 1 this week, 2 virtual items should be added to their account immediately after purchasing. If they buy Package 1 next week, 2 more virtual items should be added to their account. They should be able to edit the details of those 4 virtual items at any time. After editing those details, I need to be notified. I will also need to have the ability to send monthly invoices. It doesn't necessarily have to be automated, I can manually send out invoices every month. This is something I could also do manually in PayPal. I was thinking that WordPress might be a good platform for this. Perhaps we could modify existing eCommerce plugins such as wpEcommerce, woocmmerce or WPcommerce or maybe there are plugins like this that are out there. It doesn't matter what platform we use, I just figured WordPress might be easiest because of the amount of plugins available and the register / login system already in place. I have PSD files already created for the design of this site. They were done professionally and are properly layered. I will also need the psd files converted to HTML / CSS (either WordPress theme, html, etc). If you do not do that as a service that is okay, I can get that done by someone else. This project is mainly for the site functionality but if you are able to convert the PSD to css / html as well, please include that in your bid and tell me. Thank you in advance for helping me get this project done as inexpensively as possible.