I really don't even know what to call the Kickstarter exchanges. You're not allowed to call it a purchase because there may or may not even be a "reward" or "product", especially with projects like Reading Rainbow. It's not a donation, because they can offer rewards and are apparently required to provide them if they are successful.

They do seem to promote the idea that you're making an investment, just without the sort of potential (or scaling) returns you'd see from a conventional investment.