I built off of Nwazet.Commerce (thanks Bertrand) with a new module that extends Commerce to include PayPal! It includes PayPal Instant Payment Notification, a purchase History, and the ability to associate role assignment with a product - real nice for when
you are selling access rights to content on your website.
I will be using this in a live site shortly and be keeping this module up to date - your feedback is welcome so it can be a great module. Documentation will improve over time (i.e. there isn't any yet) but if you can figure out Nwazet.Commerce should
be all set with starting out with the above module. When you find bugs (and you likely will), please let me know.
Hope you find the module useful.