Let's have "kickstarter" for public cause!

You vote with your money, on which project you want to achieve, and if it does not raise enough money, you can spend elsewhere.

Or could be fun a "university matriculation system like" way, where you lock up a certain amount of money, and setup a list of projects you would support, then your money goes to that project that reaches the target. But then there is a higher chance of reaching the goal, because you can choose many projects.

Then you are basically paying for the things you care about, and not for the things someoneelse decides to spend your money. Which could be his pocket as well.