I notice you're repeating photos (or have a bunch of really, really similar ones). Perhaps you could get a collection going where people could send you their photos so you could make an even better mosaic (both in terms of not repeating and better color matching).
What software did you use to make that? I used AndreaMosaic for my
Team 177 Mosaic. That was about 500 photos with no repeats. We culled video frames to get filler, since even with everyones photos we still didn't have enough!