We're listening to our users and have removed the requirement to give an affiliate url to insert a link for visitors to buy and item on external sites.  We've realized that it's much more important to have a complete marketplace/directory that's easy to use with as few limitations as possible.  Now there's nothing standing in the way of Authors adding all their extensions and templates with links to download and/or purchase on their own sites!  Don't forget that you can also host your files on The Market and sell them here as well!