Selfstarter is an open source starting point for building your own ad-hoc crowdfunding site. Selftstarter is a starting point for you to build your own solution. It is set up to collect reservations using Amazon Payments, but you can choose you own provider too.
They have kept Selfstarter really simple, but that also means that you should beef it up with your own authentication, administration and product management code. Most of what you need to get started is in the Readme. Selfstarter is based on Ruby on Rails, and they have tried to break up all of the different parts in a sensible fashion.
Requirements: Ruby on Rails
License: MIT License