I think another important distinction is who is really dependent on whom. Are your success contingent on their them, and/or is their success contingent on you?

For example, Ventrilo was free to raise their rates because their success and profits really weren't dependent on the profits of the end users. They could jack their prices all over the place and most of their customers would have to pay if they wanted to keep their business going. They had lock in and they used it. They really don't care about how your company does, just that they extract maximum profit from you.

On the other hand, a company like Google has its success and profits dependent on your website being awesome. The more people who use the web and the more time they spend on it the more money Google will make. Google wants your site to succeed because it makes them money in the long run. They won't be as interested in jerking you around because they're not making money directly from you.