Need the right e-commerce plugin

I need an ecommerce plugin that’s a good fit for a handful of items, like 10-12 tops. My client sells seminars and books but on the books he only sells them if the order is 50+ so I need to be able to set minimum orders, but just for the books. It would be great if it were easy enough to use that I could train him to do it. Can anyone recommend a good plugin for this?