I am looking to add a shopping cart or something like that to my website that will allow my clients to pay for featured listings. I would also like that new clients pay a monthly fee for membership when they post their first property. I then would like an admin page to allow me to change the pricing whenever and track client information. I would also like to be able to run special pricing and promotions that will allow for limited time offers and promotion codes to be issued. I currently use paypal so I will need some sort of tracking system to know who paid and who didn't and automatically update thier file to add or remove thier properties from active searches.
I would also like it to be expandable so that I can add new items/services for sale and also so that I can add new ways to pay such as google checkout or some other merchant service.
The website address is http://www.worldwide-propertysales.com.
We use asp, .net, C# and SQL Server 2005
Only respond after having looked at the website and are for sure that you can do the project please.