Magento is a shopping cart I use at my mainstream job. The community version is a full version and free. It works well for me and can be integrated into wordpress via a free plugin.
http://www.magentocommerce.com/magen...tegration.html
When you add a product, there is a meta tab where you can put individual info for each one:
You can use PayPal, authorize.net, etc and there are plugins for some Euro based processors as well.
Anyway, the wordpress only method may be easier but I am not sure how advanced they were and just figured I would chime in about Magento as another possible option for ya.
Best of luck with it.