It always pays to shop around, and I've actually shifted more of my business to ebay for items that are quite clearly the same cheap chinese product with X name stuck on it. Amazon doesn't reliably hit its two-day shipping mandate for me, and USPS can often beat them for smaller items.

One thing I have noticed and don't really understand: Sellers who's products are more expensive on their own site than on their Amazon page. I could understand parity, but I don't understand it being more expensive to purchase from them directly.