Or, is that what "Kickstarters" means?
Kickstarter is a crowdfunding site. http://www.kickstarter.com/
The producer of the hypothetical project posts a project saying "I need this much total to get this done. If you contribute X much, you get x reward. If you contribute Y, you get y."
People then pledge contributions. If the pledges equal or exceed the posted need at the close date, the project moves to "funding" and all the pledges are collected. (Kickstarter then takes a cut, too. A few percent.) No further participants can join the kickstarter once it funds, and Kickstarter closes the project to new pledges. If, at the close date, it didn't fund, no money changes hands at all.
Then, the project hopefully completes in a timely manner, and the rewards get shipped.
In many cases, the reward is the final product, and thus kickstarter serves as a form of preorder.
T5's kickstarter funded several months ago.
The book goes to press "real soon now", and Marc's budget was way exceeded by the funded level. To the point he's going to be able to do all kinds of nifty. Much of which was the swag for participation in the kickstarter at various levels.
But Marc also budgeted so that he'd have books left for sale after meeting the preorder needs. And then, T5 became one of the largest RPG fundings on Kickstarter. So Marc isn't likely to run out.
If so, where do I sign up?
Sadly for you, you need to watch farfuture.net for the T5 books for general release to show up.