I visited an old painter's supply store in Kyoto, and purchased 15 gram plastic packets of a few pigments. The main set of pigments discussed in printmaker David Bull's writing on the subject of pigments are:

gunjo (prussian blue)
hon yoko (a type of carmine)
shin seki ei (a basic yellow)
shu (vermillion)
ai-iro (indigo)

I thought I could just ask the shopkeeper for each color by name, but I learned that actually there are many shades and varieties of gunjo, shu, ai-iro, and so on.

The prices were extremely cheap. Some pigments were ¥200, others were ¥400.