I don't think you can generalise. I started right off with my own product. If there is a free trial then lots of people use it. You don't need to build a list. If a free trial is not an option (your product is an ebook for example) then what is the difference between selling it and someone else's product?

Whatever you do you have to give something away for free or no one will pay attention to you! We're all the same at heart ;^)

I like to make a squeeze page, collect traffic to it, and hit the list with affiliate offers/give lots of value. *IF AND ONLY IF* it looks profitable will I bother having a product developed.