I got mine from LEDsee.com, the cheapest I've seen but it takes half of forever for the parts to arrive from China.
RGB - red green and blue - real tricolor
Not RG - red and green - mix to get yellow and call it tricolor
If you mix full HIGH/LOW combinations, you get seven colors plus off: RED, YELLOW, GREEN, CYAN, BLUE, MAGENTA, "WHITE."
madworm's excellent inner loop supports more steps or shades of each one, so you have 32*32*32 different colors, a 15-bit RGB color scheme. At the end of my video, I use it to produce the "girly pink" color of Pacman's nemesis Pinky.
I've expanded on it so the loop will take 24-bit color data, but it still reduces it down to 15-bits for display. This makes encoding images from existing computer bitmaps much easier, and gives room for improvement if I can make the inner loop any faster.