Earlier quoted context omitted.
The point is, this is not a model at all IMHO, since a model requires the ability to work in the long run. So you know wrote code for 1 month, and you want to be crowdsourced. Ok, what's the plan for the continued development of the project? Code as it is is worth zero without bugfixes, evolution, and a community.
A) I have written some software B) I'm debating whether to take the OSS or commercial route, since I do need money to live C) I have a reputation for maintaining software in a serious way So I'm asking people "If this is worth 10k to you, let's go the open-source route". So far, it looks as if it is worth that to people. Unless I'll turn around and act like a complete bandit, destroying my reputation, the model works…
I think there are things that play nicely with the open source model, that is, ways to make money that don't interact in a bad way with the culture of free software. I don't think that to ask to be payed to open source stuff is in line with the OSS movement / culture.
Ok, now that the hostile bit is discussed, my argument is that it makes more sense IMHO if you say, there are N people willing to donate me 10$ per year if I open source this stuff? It's still wrong IMHO as a model, but at least makes sense, that is, you will get money to provide the software relevant, updated, documented in the future.
The una tantum system instead is broken, how you'll make money in the future in order to continue the development, since it is clear you don't write this software if you are not backed in some way?