I applaud your intent, commitment and willingness to put in the effort of implementing pushing this, and I think it has a niche ("better kickstarter" isn't bad). However, I think the main problems in reality will be dealing with delivery failure/scams, transaction costs, market sizes (a lot of public goods aren't that public, minority concerns often don't  get serviced by firms because of simple non-profitability),  and threshold behaviour (when the value estimate for each person is washed out in the uncertainty noise and the refund is negligible due to fees).

You might also want to ask yourself, 

1. will you be happy if this only works for club goods? I think here the private entrepreneurial case is much stronger, and even in the original paper a lot of the discussion of strongest equilibria is for $K=N$ and club goods. 
2. What mechanisms other than "culture" can you think of to stop the "raise a bunch of money, then put ads in anyway" or other rent-seeking behaviour can you think of? If we could build a careful  culture easily, we wouldn't need mechanisms like this, and I'd argue the OS community has its strong culture because it widely rejects commercialization and profit motives (or at best begrudgingly accepts people need to eat) and instead operates in the social domain, not in the transactional domain (think of the difference of paying you 25 bucks for help me moving vs. asking you to help me move and buying pizza + drinks for 20 bucks), which you would probably lose.