Aperture has nothing to do with selling photographs. That's not what it's for. It's a photo editor, not commerce software ;-)
That said, if you use SmugMug, you can use the excellent SmugInPro plug-in which can do round-trip with Aperture (it will let you replace SmugMug photos in-place). So if you set prices on your galleries in SmugMug, it's easy.
Thanks for the response. I know that this is not the role of aperture itself. As you mentioned I do use the plugin to place photographs (exporttosmugmug plugin) and I was looking to see if anyone knew of a similar plugin that would export to say Pages where I could add in pricing information and create a printable catalog. I know sites do this (not smugmug but say fineartamerica.com) I am just looking for a way I can do this myself for my photos hanging in a local gallery. Perhaps I need to create a plugin or at the very least a Pages template to help out others desiring this.
In Aperture you can create both Books and Web pages so one of these might fix your need. You could look into creating a theme for doing the pricing stuff in either.
Creating a theme is a lot easier than creating a plug-in.
If you want to do the work in Pages creating a Script that would export the images from Aperture and then manipulate them in Pages is also an option.