As a (hypothetical) company with an API of my own, I'd be willing to pay to become a supported channel. This may be unwise initially -- once ifttt's third-party API is ready they'll want as many services as possible on board to strengthen the value proposition -- but perhaps there are scenarios where it makes sense. That is, charge the companies benefitting from increased traffic and awareness rather than the individuals using the system.
There are plenty of examples (Apple being the first one that comes to mind) of companies who charge a ton (and make a ton of money) for a product that is available elsewhere for cheaper.
Price isn't always everything in the consumers mind.
