website portal (customizable site templates) <a target="_new" href="http://dotnetnuke.com/">dotnetnuke.com/</a>. you might find dotnetnuke has some online store components for it (I've used phpnuke and know they have quite a few for theirs, but this is a completely different project).
mosessaur has an online store: <a target="_new" href="http://prostore.europe.webmatrixhosting.net/">prostore.europe.webmatrixhosting.net/</a> here's the thread talking about it: <a target="_new" href="http://www.csharpfriends.com/Forums/ShowPost.aspx?PostID=16502">csharpfriends.com/Forums/ShowPost.aspx?PostID=16502</a>, you should be able to get the source from there (links are posted in the thread)
hope this helps.