Juke,
You are right, Paypal is good for simple products, and if you are am Amazon affiliates then Amazon codes should do it for you. oscommerce is a well established solid produce but the biggest downside is what you have correctly identified.
I use my own in house developed shopping cart, its called
iG Shop. I made it available as and open source product, it was quite popular when I first made it available, but I have not had time to develop it further. I will hopefully do more development on it next year. I have used iG Shop to build quite a few e-commerce sites for my customers, the latest one is a
Golf Equipment ShopGolf Equipment Shop[/url] which is going quite well now.
I am also working on another e-commerce shopping cart which I am building with the experience and knowledge gain from iG Shop, the new shopping carts greatest strength is its search engine friendliness. Search engines will be able to spider absolutely every produce in your database. It will also come with a utility that helps you export your product to Froogle and keep and inventory of your stock level.
Its an exciting project and I look forward to getting the first edition out early next year
Temi