@indemnifyme - I love to shop online myself, so I can see why your boss likes to procure your supplies online.
I wanted to reiterate what the article said about using the same companies. My office works with a few companies on a regular basis and it's been very beneficial. We've been working with one of the companies for years and developed a really good relationship with them. I don't think we would get the same kind of deals and service from a company we had just started dealing with.