I've run a couple of e-commerce sites of my own in the past and I was usually provided with images via the wholesaler/manufacturer I was buying from. Almost all are hidden away in a password protected "media" section on their website which is often not even listed on their sitemap etc. One company that doesn't hide their product images away is Apple (http://www.apple.com/uk/pr/products/) but I'm not totally sure what the law is around copyright given that you are using them as examples (I doubt any enlightened companies would bother taking you to court over such a thing given that it's basically free promotion!)