I remember there was a discussion on donations (initiated by people who want to donate), and the team didn’t want that.
Well, how about this? Many open-source projects use bountysource these days (this is OpenRA’s page for example), where people can sponsor development of certain features (RMG, battle AI, etc.).
Aside from letting people who want to donate in some way, this can also attract other people to contribute to the project (hence it should also be OK with “developer time is better than donations for us”).
As a bonus, bountysource can be integrated in GitHub issue list.