Kickstarter is really about funding a project, not really about selling merchandise. You can put "perks" for various funding levels, and many projects use the product as a perk at some level, but you don't have to. And KS lets you put limits on rewards. For example the DoubleFine page says
Pledge $1,000 or more
84 Backers • Limited Reward (16 of 100 remaining)
Mini portrait of YOU, painted by the game's artist, and all previous reward tiers.
Pledge $1,000 or more 84 Backers • Limited Reward (16 of 100 remaining)
Mini portrait of YOU, painted by the game's artist, and all previous reward tiers.