as for "waiting to donate" let me give a (almost) completely made-up example:
We're considering which NFC chip to use for Neo900. The NXP stuff (PN544) is basically fine but lacks lots of needed documentation that's not freely available. Now when I ask NXP to disclose that docs to me, what do you think has higher chances to receive a positive answer:
"estimated number of devices to build containing the chip you want docs for: 250"
or
"estimated number of devices to build containing the chip you want docs for: 800"
Maybe we even had to already buy the chips to get the docs we need. So we would do it. Currently we would probably buy 400 chips, based on number of donations which we count as "preorders".
Every donor takes the risk that this project might fail and no fine shiny product emerges at the end of R&D at all (though the developers themselves [=Neo900 group] are highly eager to have such device for their own daily phone. And shown that they can actually accomplish the task of building such device, since they done before), or the product is not as shiny as it been planned to be, and every donor supports the project by donation as early as possible of as much as they feel they can spare and "risk", to make it more likely to succeed and achieve a great result. For example we might not be able to get 1GB of RAM when the number of donations/preorders is too low for MOQ of that chip. Those donations are what makes the whole project happen, since we don't want to go for commercial venture capital (aka "investors", with only commercial interests of ROI) that then dictates which mainstream requirements the final product must satisfy, to maximize the win margin. The Neo900 fundraising is unique in that it offers "payback" of donations >=100EUR since we think it's only fair that those who supported the project early shall get a product as result of such support for a total expense not higher than, or -ideally- even cheaper than, what a late customer whould have to pay. As added benefit all our supporters / donors participate in the development and it's them and their wishes we design the device for. We will consider their wishes more important for the design than the wishes some non-donor utters. In that sense it's actually a community project, though the business parts (incl final responsibility and decisions) are clearly non-community but commercial.

BR
jOERG