I wasn't thinking along the lines of collecting money up front and I think it would be dangerous to go down that path. On thinking about it, the term "Crowd Funding" isn't appropriate for what I had in mind, but it was the correct term when the concept appeared many years ago. One of my hobbies is model railroading and people often express an interest in a particular locomotive design and ask if anyone is interested in making it. A manufacturer may respond by saying he or she will take on the job if they get xxx expressions of interest. Once they reach the target, those interested are contacted to ensure they're genuinely prepared to pay and then the manufacturer will proceed with production. In some instances a small deposit is requested, but generally the manufacturer is satisfied with the pledge. I may point out that in one recent case, it took five years for the product to eventuate, but it did.
I think the idea of paying someone in advance is very dangerous, especially in the IT world. Thus I was thinking of pledges, which people sometimes forget they're ever made, but the developer can usually count on some money being available at the end of the day. If I knew the developer, I may be willing to pay 25% up front, but I wouldn't be doing it for someone I knew nothing about.
I think my original suggestion to Modzzz, was a mod where people could suggest a module and others could say they would also be prepared to purchase a copy. A value would be set (say $20). If a developer was interested in taking the project on, he would tag it as such and develop it. He would then negotiate with the interested parties for payment of the value stated, but also offer the module on the market for a higher price if he wished.
My suggestion was to encourage a developer to create a module for the market, not for members to pay the full cost of development.