I bought one of the bags of buttons from Fabric Mart (http://fabricmartfabrics.com/). It is quite impressive.
The photo shows the sorting I've done - about half the bag (that is the other half on the upper left. I'm going to have to find something to use all those purple buttons on. There are some nice black and white buttons. Lots of neutral colors. And as you can see, varying amounts of the different styles. So far, just one pink, two turquoise and three yellow! There are a slew of dark green and some nice blue.
So if you've been wondering - this is what the bag looks like!