Hm. You actually made me look at it, and it indeed does look interesting. Somehow, I always had an unfavourable impression about BountySource before; now that I think of it, possibly because of clunky GUI? Or, I believe it may be that the "capturing/overlaying" of GitHub Issues they do feels uncannily scammy to me?
Edit: don't fully understand it, but somehow I have a feeling it'd help me if I saw people behind the project emphasized more? I now remember I also supported the Voxel Quest author (Gavan Woolery) via his project. The "regular" (non-Kickstarter) one however was Calibre.