Then do the Patreon model where the modder is "hired" by the community. The modder/s decide a minimum wage, and then see if the community is willing to continue to support the mod creation.
The beautiful aspect of this compared to selling products is that everyone involve know what is expected from each other, the responsibility to fix bugs is established in the beginning, and its very hard to sell someones else mod as your own.
There is a former maxis employee doing exactly that for high quality building mods in cities :skyline. Its working well for him, but that has partly to do with the his former job, the pure quality of his work, and the press attention hes garnered. I suspect it was the timing of maxis closing and Cities releasing that helped the most, although his models are excellent in every way. Its just that even with great art, without some attention you will languish.
It would be a great thing if Valve implemented a Patreon model for modding instead of direct pay. That would let people get the attention their great work deserves, streamline donations, and not change the nature of the modding community in the process.
A black and white webcomic I read runs a patreon page, and get $3k a month with only 800 patrons. The author was previously unknown, and managed to reach this point purely on the quality of his/her work and the readership it gathered. Looking at some of the major skyrim mods with millions of downloads, I suspect they could easily gain more than 800 patrons.
Yes, to use your slightly off description. But there's nothing wrong with that if the people offering the money understand what the expectations are before donating.
The beautiful aspect of this compared to selling products is that everyone involve know what is expected from each other, the responsibility to fix bugs is established in the beginning, and its very hard to sell someones else mod as your own.