Ask HN: What payment platform can accept pledges?

Friends, I'm considering building an app where people can pledge money towards a particular product before it has been created. Similar in concept to KickStarter but driven more towards direct pre-purchase of consumer goods. The one thing that seems different than a "regular" pre-order here is that the product's creation is conditional. It may never be created and therefore the customer wouldn't be charged. I've looked at various payment processors (recurly.com, cheddargetter.com, chargify.com) and it isn't clear to me that this kind of payment is possible with their systems. Have you had any experience taking pledges? 1) If so, what service did you use (or did you roll your own)? 2) If I have to roll my own, any advice on potential pitfalls?